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Mathematics LibreTexts

4.2: Percents Problems and Applications of Percent

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  • Page ID 142718

  • Morgan Chase
  • Clackamas Community College via OpenOregon

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You may use a calculator throughout this module.

sale-tag.jpg

Recall: The amount is the answer we get after finding the percent of the original number. The base is the original number, the number we find the percent of. We can call the percent the rate.

When we looked at percents in a previous module, we focused on finding the amount. In this module, we will learn how to find the percentage rate and the base.

\(\text{Amount}=\text{Rate}\cdot\text{Base}\)

\(A=R\cdot{B}\)

We can translate from words into algebra.

  • “is” means equals
  • “of” means multiply
  • “what” means a variable

Solving Percent Problems: Finding the Rate

Suppose you earned \(56\) points on a \(60\)-point quiz. To figure out your grade as a percent, you need to answer the question “\(56\) is what percent of \(60\)?” We can translate this sentence into the equation \(56=R\cdot60\).

Exercises \(\PageIndex{1}\)

1. \(56\) is what percent of \(60\)?

2. What percent of \(120\) is \(45\)?

1. \(93\%\) or \(93.3\%\)

2. \(37.5\%\)

Be aware that this method gives us the answer in decimal form and we must move the decimal point to convert the answer to a percent.

Also, if the instructions don’t explicitly tell you how to round your answer, use your best judgment: to the nearest whole percent or nearest tenth of a percent, to two or three significant figures, etc.

Solving Percent Problems: Finding the Base

Suppose you earn \(2\%\) cash rewards for the amount you charge on your credit card. If you want to earn $ \(50\) in cash rewards, how much do you need to charge on your card? To figure this out, you need to answer the question “\(50\) is \(2\%\) of what number?” We can translate this into the equation \(50=0.02\cdot{B}\).

3. $ \(50\) is \(2\%\) of what number?

4. \(5\%\) of what number is \(36\)?

3. $ \(2,500\)

5. An \(18\%\) tip will be added to a dinner that cost $ \(107.50\). What is the amount of the tip?

6. The University of Oregon women’s basketball team made \(13\) of the \(29\) three-points shots they attempted during a game against UNC. What percent of their three-point shots did the team make?

7. \(45\%\) of the people surveyed answered “yes” to a poll question. If \(180\) people answered “yes”, how many people were surveyed altogether?

5. $ \(19.35\)

6. \(44.8\%\) or \(45\%\)

7. \(400\) people were surveyed

Solving Percent Problems: Percent Increase

When a quantity changes, it is often useful to know by what percent it changed. If the price of a candy bar is increased by \(50\) cents, you might be annoyed because it’s it’s a relatively large percentage of the original price. If the price of a car is increased by \(50\) cents, though, you wouldn’t care because it’s such a small percentage of the original price.

To find the percent of increase:

  • Subtract the two numbers to find the amount of increase.
  • Using this result as the amount and the original number as the base, find the unknown percent.

Notice that we always use the original number for the base, the number that occurred earlier in time. In the case of a percent increase, this is the smaller of the two numbers.

8. The price of a candy bar increased from $ \(0.89\) to $ \(1.39\). By what percent did the price increase?

9. The population of Portland in 2010 was \(583,793\). The estimated population in 2019 was \(654,741\). Find the percent of increase in the population. [1]

8. \(56.2\%\) increase

9. \(12.2\%\) increase

Solving Percent Problems: Percent Decrease

Finding the percent decrease in a number is very similar.

To find the percent of decrease:

  • Subtract the two numbers to find the amount of decrease.

Again, we always use the original number for the base, the number that occurred earlier in time. For a percent decrease, this is the larger of the two numbers.

10. During a sale, the price of a candy bar was reduced from $ \(1.39\) to $ \(0.89\). By what percent did the price decrease?

11. The number of students enrolled at Clackamas Community College decreased from \(7,439\) in Summer 2019 to \(4,781\) in Summer 2020. Find the percent of decrease in enrollment.

10. \(36.0\%\) decrease

11. \(35.7\%\) decrease

Relative Error

In an earlier module, we said that a measurement will always include some error, no matter how carefully we measure. It can be helpful to consider the size of the error relative to the size of what is being measured. As we saw in the examples above, a difference of \(50\) cents is important when we’re pricing candy bars but insignificant when we’re pricing cars. In the same way, an error of an eighth of an inch could be a deal-breaker when you’re trying to fit a screen into a window frame, but an eighth of an inch is insignificant when you’re measuring the length of your garage.

The expected outcome is what the number would be in a perfect world. If a window screen is supposed to be exactly \(25\) inches wide, we call this the expected outcome, and we treat it as though it has infinitely many significant digits. In theory, the expected outcome is \(25.000000...\)

To find the absolute error , we subtract the measurement and the expected outcome. Because we always treat the expected outcome as though it has unlimited significant figures, the absolute error should have the same precision (place value) as the measurement , not the expected outcome .

To find the relative error , we divide the absolute error by the expected outcome. We usually express the relative error as a percent. In fact, the procedure for finding the relative error is identical to the procedures for finding a percent increase or percent decrease!

To find the relative error:

  • Subtract the two numbers to find the absolute error.
  • Using the absolute error as the amount and the expected outcome as the base, find the unknown percent.

Exercisew \(\PageIndex{1}\)

12. A window screen is measured to be \(25\dfrac{3}{16}\) inches wide instead of the advertised \(25\) inches. Determine the relative error, rounded to the nearest tenth of a percent.

13. The contents of a box of cereal are supposed to weigh \(10.8\) ounces, but they are measured at \(10.67\) ounces. Determine the relative error, rounded to the nearest tenth of a percent.

12. \(0.1875\div25\approx0.8\%\)

13. \(0.13\div10.8\approx1.2\%\)

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The tolerance is the maximum amount that a measurement is allowed to differ from the expected outcome. For example, the U.S. Mint needs its coins to have a consistent size and weight so that they will work in vending machines. A dime (10 cents) weighs \(2.268\) grams, with a tolerance of \(\pm0.091\) grams. [2] This tells us that the minimum acceptable weight is \(2.268-0.091=2.177\) grams, and the maximum acceptable weight is \(2.268+0.091=2.359\) grams. A dime with a weight outside of the range \(2.177\leq\text{weight}\leq2.359\) would be unacceptable.

dime-under-microscope-300x225.jpg

A U.S. nickel (5 cents) weighs \(5.000\) grams with a tolerance of \(\pm0.194\) grams.

14. Determine the lowest acceptable weight and highest acceptable weight of a nickel.

15. Determine the relative error of a nickel that weighs \(5.21\) grams.

A U.S. quarter (25 cents) weighs \(5.670\) grams with a tolerance of \(\pm0.227\) grams.

16. Determine the lowest acceptable weight and highest acceptable weight of a quarter.

17. Determine the relative error of a quarter that weighs \(5.43\) grams.

14. \(4.806\) g; \(5.194\) g

15. \(0.21\div5.000=4.2\%\)

16. \(5.443\) g; \(5.897\) g

17. \(0.24\div5.670\approx4.2\%\)

  • www.census.gov/quickfacts/fact/table/portlandcityoregon,OR,US/PST045219 ↵
  • https://www.usmint.gov/learn/coin-and-medal-programs/coin-specifications and https://www.thesprucecrafts.com/how-much-do-coins-weigh-4171330 ↵
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How to Solve Percent Problems? (+FREE Worksheet!)

Learn how to calculate and solve percent problems using the percent formula.

How to Solve Percent Problems? (+FREE Worksheet!)

Related Topics

  • How to Find Percent of Increase and Decrease
  • How to Find Discount, Tax, and Tip
  • How to Do Percentage Calculations
  • How to Solve Simple Interest Problems

Step by step guide to solve percent problems

  • In each percent problem, we are looking for the base, or part or the percent.
  • Use the following equations to find each missing section. Base \(= \color{black}{Part} \ ÷ \ \color{blue}{Percent}\) \(\color{ black }{Part} = \color{blue}{Percent} \ ×\) Base \(\color{blue}{Percent} = \color{ black }{Part} \ ÷\) Base

Percent Problems – Example 1:

\(2.5\) is what percent of \(20\)?

In this problem, we are looking for the percent. Use the following equation: \(\color{blue}{Percent} = \color{ black }{Part} \ ÷\) Base \(→\) Percent \(=2.5 \ ÷ \ 20=0.125=12.5\%\)

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Percent problems – example 2:.

\(40\) is \(10\%\) of what number?

Use the following formula: Base \(= \color{ black }{Part} \ ÷ \ \color{blue}{Percent}\) \(→\) Base \(=40 \ ÷ \ 0.10=400\) \(40\) is \(10\%\) of \(400\).

Percent Problems – Example 3:

\(1.2\) is what percent of \(24\)?

In this problem, we are looking for the percent. Use the following equation: \(\color{blue}{Percent} = \color{ black }{Part} \ ÷\) Base \(→\) Percent \(=1.2÷24=0.05=5\%\)

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Percent problems – example 4:.

\(20\) is \(5\%\) of what number?

Use the following formula: Base \(= \color{black}{Part} \ ÷ \ \color{blue}{Percent}\) \(→\) Base \(=20÷0.05=400\) \( 20\) is \(5\%\) of \(400\).

Exercises for Calculating Percent Problems

Solve each problem..

  • \(51\) is \(340\%\) of what?
  • \(93\%\) of what number is \(97\)?
  • \(27\%\) of \(142\) is what number?
  • What percent of \(125\) is \(29.3\)?
  • \(60\) is what percent of \(126\)?
  • \(67\) is \(67\%\) of what?

Download Percent Problems Worksheet

  • \(\color{blue}{15}\)
  • \(\color{blue}{104.3}\)
  • \(\color{blue}{38.34}\)
  • \(\color{blue}{23.44\%}\)
  • \(\color{blue}{47.6\%}\)
  • \(\color{blue}{100}\)

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by: Effortless Math Team about 5 years ago (category: Articles , Free Math Worksheets )

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Solving Percent Problems

Videos to help Grade 6 students solve percent problems. When given a part and the percent, students find the percent of a quantity and solve problems involving finding the whole.

New York State Common Core Math Module 1, Grade 6, Lesson 29

Lesson 29 outcome.

• Students find the percent of a quantity. • Given a part and the percent, students solve problems involving finding the whole.

Lesson 29 Summary

Claim: To find 10% of a number all you need to do is move the decimal to the left once.

Use at least one model to solve each problem (e.g., tape diagram, table, double number line diagram, 10x10 grid).

Claim: If an item is already on sale and then there is another discount taken off the sale price, this is the same as saving the sum of the two discounts from the original price.

Use at least one model to solve each problem (e.g., tape diagram, table, double number line diagram, 10 x 10 grid).

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Percentages Worksheets

Welcome to the percentages math worksheet page where we are 100% committed to providing excellent math worksheets. This page includes Percentages worksheets including calculating percentages of a number, percentage rates, and original amounts and percentage increase and decrease worksheets.

As you probably know, percentages are a special kind of decimal. Most calculations involving percentages involve using the percentage in its decimal form. This is achieved by dividing the percentage amount by 100. There are many worksheets on percentages below. In the first few sections, there are worksheets involving the three main types of percentage problems: calculating the percentage value of a number, calculating the percentage rate of one number compared to another number, and calculating the original amount given the percentage value and the percentage rate.

Most Popular Percentages Worksheets this Week

Calculating the Percent Rate of Whole Number Amounts and All Percents

Percentage Calculations

solving problems involving percents

Calculating the percentage value of a number involves a little bit of multiplication. One should be familiar with decimal multiplication and decimal place value before working with percentage values. The percentage value needs to be converted to a decimal by dividing by 100. 18%, for example is 18 ÷ 100 = 0.18. When a question asks for a percentage value of a number, it is asking you to multiply the two numbers together.

Example question: What is 18% of 2800? Answer: Convert 18% to a decimal and multiply by 2800. 2800 × 0.18 = 504. 504 is 18% of 2800.

  • Calculating the Percentage Value (Whole Number Results) Calculating the Percentage Value (Whole Number Results) (Percents from 1% to 99%) Calculating the Percentage Value (Whole Number Results) (Select percents) Calculating the Percentage Value (Whole Number Results) (Percents that are multiples of 5%) Calculating the Percentage Value (Whole Number Results) (Percents that are multiples of 25%)
  • Calculating the Percentage Value (Decimal Number Results) Calculating the Percentage Value (Decimal Number Results) (Percents from 1% to 99%) Calculating the Percentage Value (Decimal Number Results) (Select percents) Calculating the Percentage Value (Decimal Number Results) (Percents that are multiples of 5%) Calculating the Percentage Value (Decimal Number Results) (Percents that are multiples of 25%)
  • Calculating the Percentage Value (Whole Dollar Results) Calculating the Percentage Value (Whole Dollar Results) (Percents from 1% to 99%) Calculating the Percentage Value (Whole Dollar Results) (Select percents) Calculating the Percentage Value (Whole Dollar Results) (Percents that are multiples of 5%) Calculating the Percentage Value (Whole Dollar Results) (Percents that are multiples of 25%)
  • Calculating the Percentage Value (Decimal Dollar Results) Calculating the Percentage Value (Decimal Dollar Results) (Percents from 1% to 99%) Calculating the Percentage Value (Decimal Dollar Results) (Select percents) Calculating the Percentage Value (Decimal Dollar Results) (Percents that are multiples of 5%) Calculating the Percentage Value (Decimal Dollar Results) (Percents that are multiples of 25%)

Calculating what percentage one number is of another number is the second common type of percentage calculation. In this case, division is required followed by converting the decimal to a percentage. If the first number is 100% of the value, the second number will also be 100% if the two numbers are equal; however, this isn't usually the case. If the second number is less than the first number, the second number is less than 100%. If the second number is greater than the first number, the second number is greater than 100%. A simple example is: What percentage of 10 is 6? Because 6 is less than 10, it must also be less than 100% of 10. To calculate, divide 6 by 10 to get 0.6; then convert 0.6 to a percentage by multiplying by 100. 0.6 × 100 = 60%. Therefore, 6 is 60% of 10.

Example question: What percentage of 3700 is 2479? First, recognize that 2479 is less than 3700, so the percentage value must also be less than 100%. Divide 2479 by 3700 and multiply by 100. 2479 ÷ 3700 × 100 = 67%.

  • Calculating the Percentage a Whole Number is of Another Whole Number Calculating the Percentage a Whole Number is of Another Whole Number (Percents from 1% to 99%) Calculating the Percentage a Whole Number is of Another Whole Number (Select percents) Calculating the Percentage a Whole Number is of Another Whole Number (Percents that are multiples of 5%) Calculating the Percentage a Whole Number is of Another Whole Number (Percents that are multiples of 25%)
  • Calculating the Percentage a Decimal Number is of a Whole Number Calculating the Percentage a Decimal Number is of a Whole Number (Percents from 1% to 99%) Calculating the Percentage a Decimal Number is of a Whole Number (Select percents) Calculating the Percentage a Decimal Number is of a Whole Number (Percents that are multiples of 5%) Calculating the Percentage a Decimal Number is of a Whole Number (Percents that are multiples of 25%)
  • Calculating the Percentage a Whole Dollar Amount is of Another Whole Dollar Amount Calculating the Percentage a Whole Dollar Amount is of Another Whole Dollar Amount (Percents from 1% to 99%) Calculating the Percentage a Whole Dollar Amount is of Another Whole Dollar Amount (Select percents) Calculating the Percentage a Whole Dollar Amount is of Another Whole Dollar Amount (Percents that are multiples of 5%) Calculating the Percentage a Whole Dollar Amount is of Another Whole Dollar Amount (Percents that are multiples of 25%)
  • Calculating the Percentage a Decimal Dollar Amount is of a Whole Dollar Amount Calculating the Percentage a Decimal Dollar Amount is of a Whole Dollar Amount (Percents from 1% to 99%) Calculating the Percentage a Decimal Dollar Amount is of a Whole Dollar Amount (Select percents) Calculating the Percentage a Decimal Dollar Amount is of a Whole Dollar Amount (Percents that are multiples of 5%) Calculating the Percentage a Decimal Dollar Amount is of a Whole Dollar Amount (Percents that are multiples of 25%)

The third type of percentage calculation involves calculating the original amount from the percentage value and the percentage. The process involved here is the reverse of calculating the percentage value of a number. To get 10% of 100, for example, multiply 100 × 0.10 = 10. To reverse this process, divide 10 by 0.10 to get 100. 10 ÷ 0.10 = 100.

Example question: 4066 is 95% of what original amount? To calculate 4066 in the first place, a number was multiplied by 0.95 to get 4066. To reverse this process, divide to get the original number. In this case, 4066 ÷ 0.95 = 4280.

  • Calculating the Original Amount from a Whole Number Result and a Percentage Calculating the Original Amount (Percents from 1% to 99%) ( Whole Numbers ) Calculating the Original Amount (Select percents) ( Whole Numbers ) Calculating the Original Amount (Percents that are multiples of 5%) ( Whole Numbers ) Calculating the Original Amount (Percents that are multiples of 25%) ( Whole Numbers )
  • Calculating the Original Amount from a Decimal Number Result and a Percentage Calculating the Original Amount (Percents from 1% to 99%) ( Decimals ) Calculating the Original Amount (Select percents) ( Decimals ) Calculating the Original Amount (Percents that are multiples of 5%) ( Decimals ) Calculating the Original Amount (Percents that are multiples of 25%) ( Decimals )
  • Calculating the Original Amount from a Whole Dollar Result and a Percentage Calculating the Original Amount (Percents from 1% to 99%) ( Dollar Amounts and Whole Numbers ) Calculating the Original Amount (Select percents) ( Dollar Amounts and Whole Numbers ) Calculating the Original Amount (Percents that are multiples of 5%) ( Dollar Amounts and Whole Numbers ) Calculating the Original Amount (Percents that are multiples of 25%) ( Dollar Amounts and Whole Numbers )
  • Calculating the Original Amount from a Decimal Dollar Result and a Percentage Calculating the Original Amount (Percents from 1% to 99%) ( Dollar Amounts and Decimals ) Calculating the Original Amount (Select percents) ( Dollar Amounts and Decimals ) Calculating the Original Amount (Percents that are multiples of 5%) ( Dollar Amounts and Decimals ) Calculating the Original Amount (Percents that are multiples of 25%) ( Dollar Amounts and Decimals )
  • Mixed Percentage Calculations with Whole Number Percentage Values Mixed Percentage Calculations (Percents from 1% to 99%) ( Whole Numbers ) Mixed Percentage Calculations (Select percents) ( Whole Numbers ) Mixed Percentage Calculations (Percents that are multiples of 5%) ( Whole Numbers ) Mixed Percentage Calculations (Percents that are multiples of 25%) ( Whole Numbers )
  • Mixed Percentage Calculations with Decimal Percentage Values Mixed Percentage Calculations (Percents from 1% to 99%) ( Decimals ) Mixed Percentage Calculations (Select percents) ( Decimals ) Mixed Percentage Calculations (Percents that are multiples of 5%) ( Decimals ) Mixed Percentage Calculations (Percents that are multiples of 25%) ( Decimals )
  • Mixed Percentage Calculations with Whole Dollar Percentage Values Mixed Percentage Calculations (Percents from 1% to 99%) ( Dollar Amounts and Whole Numbers ) Mixed Percentage Calculations (Select percents) ( Dollar Amounts and Whole Numbers ) Mixed Percentage Calculations (Percents that are multiples of 5%) ( Dollar Amounts and Whole Numbers ) Mixed Percentage Calculations (Percents that are multiples of 25%) ( Dollar Amounts and Whole Numbers )
  • Mixed Percentage Calculations with Decimal Dollar Percentage Values Mixed Percentage Calculations (Percents from 1% to 99%) ( Dollar Amounts and Decimals ) Mixed Percentage Calculations (Select percents) ( Dollar Amounts and Decimals ) Mixed Percentage Calculations (Percents that are multiples of 5%) ( Dollar Amounts and Decimals ) Mixed Percentage Calculations (Percents that are multiples of 25%) ( Dollar Amounts and Decimals )

Percentage Increase/Decrease Worksheets

solving problems involving percents

The worksheets in this section have students determine by what percentage something increases or decreases. Each question includes an original amount and a new amount. Students determine the change from the original to the new amount using a formula: ((new - original)/original) × 100 or another method. It should be straight-forward to determine if there is an increase or a decrease. In the case of a decrease, the percentage change (using the formula) will be negative.

  • Percentage Increase/Decrease With Whole Number Percentage Values Percentage Increase/Decrease Whole Numbers with 1% Intervals Percentage Increase/Decrease Whole Numbers with 5% Intervals Percentage Increase/Decrease Whole Numbers with 25% Intervals
  • Percentage Increase/Decrease With Decimal Number Percentage Values Percentage Increase/Decrease Decimals with 1% Intervals Percentage Increase/Decrease Decimals with 5% Intervals Percentage Increase/Decrease Decimals with 25% Intervals
  • Percentage Increase/Decrease With Whole Dollar Percentage Values Percentage Increase/Decrease Whole Dollar Amounts with 1% Intervals Percentage Increase/Decrease Whole Dollar Amounts with 5% Intervals Percentage Increase/Decrease Whole Dollar Amounts with 25% Intervals
  • Percentage Increase/Decrease With Decimal Dollar Percentage Values Percentage Increase/Decrease Decimal Dollar Amounts with 1% Intervals Percentage Increase/Decrease Decimal Dollar Amounts with 5% Intervals Percentage Increase/Decrease Decimal Dollar Amounts with 25% Intervals

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Solving Percent Problems

Learning Objective(s)

·          Identify the amount, the base, and the percent in a percent problem.

·          Find the unknown in a percent problem.

Introduction

Percents are a ratio of a number and 100. So they are easier to compare than fractions, as they always have the same denominator, 100. A store may have a 10% off sale. The amount saved is always the same portion or fraction of the price, but a higher price means more money is taken off. Interest rates on a saving account work in the same way. The more money you put in your account, the more money you get in interest. It’s helpful to understand how these percents are calculated.

Parts of a Percent Problem

Jeff has a coupon at the Guitar Store for 15% off any purchase of $100 or more. He wants to buy a used guitar that has a price tag of $220 on it. Jeff wonders how much money the coupon will take off the original $220 price.

Problems involving percents have any three quantities to work with: the percent , the amount , and the base .

The percent has the percent symbol (%) or the word “percent.” In the problem above, 15% is the percent off the purchase price.

The base is the whole amount. In the problem above, the whole price of the guitar is $220, which is the base.

The amount is the number that relates to the percent. It is always part of the whole. In the problem above, the amount is unknown. Since the percent is the percent off , the amount will be the amount off of the price .

You will return to this problem a bit later. The following examples show how to identify the three parts, the percent, the base, and the amount.

Problem

 

The percent is the number with the % symbol: .

 

 

The amount based on the percent is .

Percent = 20%

Amount = 30

Base = unknown

The previous problem states that 30 is a portion of another number. That means 30 is the amount. Note that this problem could be rewritten: 20% of what number is 30?

Identify the percent, base, and amount in this problem:

 

What percent of 30 is 3?

 

percent?” The base is the whole in the situation, so the base is 30. The amount is the portion of the whole, which is 3 in this case.

 

Solving with Equations

Percent problems can be solved by writing equations. An equation uses an equal sign (= ) to show that two mathematical expressions have the same value.

Percents are fractions, and just like fractions, when finding a percent (or fraction, or portion) of another amount, you multiply.

The percent of the base is the amount.

Percent of the Base is the Amount.

Percent · Base = Amount

Problem

 

20% of what number is 30?

Rewrite the problem in the form “percent of base is amount.”

 

Percent is:   20%

Base is:       unknown

Amount is:   30

Identify the percent, the base, and the amount.

 

Percent · Base = Amount

     20% ·  = 30

Write the percent equation. using for the base, which is the unknown value.

20% · = 30.

 

Once you have an equation, you can solve it and find the unknown value. To do this, think about the relationship between multiplication and division. Look at the pairs of multiplication and division facts below, and look for a pattern in each row.

2 · 3 = 6

6 ÷ 2 = 3

8 · 5 = 40

40 ÷ 8 = 5

7 · 4 = 28

28 ÷ 7 = 4

6 · 9 = 54

54 ÷ 6 = 9

Multiplication and division are inverse operations. What one does to a number, the other “undoes.”

When you have an equation such as 20% · n = 30, you can divide 30 by 20% to find the unknown: n =  30 ÷ 20%.

You can solve this by writing the percent as a decimal or fraction and then dividing.

n = 30 ÷ 20% =  30 ÷ 0.20 = 150

Problem

 

Percent: unknown

Base:     72

Amount: 9

Identify the percent, base, and amount.

 

· 72 = 9

Write the percent equation: Percent · Base = Amount. Use for the unknown (percent).

 

= 9 ÷ 72

Divide to undo the multiplication of times 72.

 

, the unknown.

= 0.125

 

= 12.5%

Move the decimal point two places to the right to write the decimal as a percent.

12.5% of 72 is 9.

 

You can estimate to see if the answer is reasonable. Use 10% and 20%, numbers close to 12.5%, to see if they get you close to the answer.

10% of 72 = 0.1 · 72 = 7.2

20% of 72 = 0.2 · 72 = 14.4

Notice that 9 is between 7.2 and 14.4, so 12.5% is reasonable since it is between 10% and 20%.

Problem

 

Percent:  110%

Base:      24

Amount:  unknown

Identify the percent, the base, and the amount.

 

110% · 24 =

Write the percent equation. Percent · Base = Amount.

The amount is unknown, so use .

 

1.10 · 24 =

 

 

1.10 · 24 = 26.4 =

Write the percent as a decimal by moving the decimal point two places to the left.

 

Multiply 24 by 1.10 or 1.1.

26.4 is 110% of 24.

 

This problem is a little easier to estimate. 100% of 24 is 24. And 110% is a little bit more than 24. So, 26.4 is a reasonable answer.

18 is what percent of 48?

 

A) 0.375%

B) 8.64%

C) 37.5%

D) 864%

 

Incorrect. You may have calculated properly, but you forgot to move the decimal point when you rewrote your answer as a percent. The equation for this problem is · 48 = 18. The corresponding division is 18 ÷ 48, so = 0.375. Rewriting this decimal as a percent gives the correct answer, 37.5%.

 

B) 8.64%

Incorrect. You may have used 18 or 48 as the percent, rather than the amount or base.

The equation for this problem is · 48 = 18. The corresponding division is 18 ÷ 48, so = 0.375. Rewriting this decimal as a percent gives the correct answer, 37.5%.

 

C) 37.5%

Correct. The equation for this problem is · 48 =18. The corresponding division is 18 ÷ 48, so = 0.375. Rewriting this decimal as a percent gives 37.5%.

 

D) 864%

Incorrect. You probably used 18 or 48 as the percent, rather than the amount or base, and also forgot to rewrite the percent as a decimal before multiplying. The equation for this problem is · 48 =18. The corresponding division is 18 ÷ 48, so = 0.375. Rewriting this decimal as a percent gives the correct answer, 37.5%.

 

Using Proportions to Solve Percent Problems

Problem

 

 =

The percent in this problem is 20%. Write this percent in fractional form, with 100 as the denominator.

 

The percent is written as the ratio , the amount is 30, and the base is unknown.

 

 

      20 • = 30 • 100

20 • = 3,000

                = 3,000 ÷ 20

= 150

Cross multiply and solve for the unknown, , by dividing 3,000 by 20.

30 is 20% of 150.

 

Problem

 

 Percent =

 

 

The percent is the ratio of to 100. The amount is 9, and the base is 72.

 

72 = 9 • 100

• 72 = 900

= 900 ÷ 72

= 12.5

Cross multiply and solve for by dividing 900 by 72.

 

 

The percent is = 12.5%.

Problem

 

Percent =

 

 

The percent is the ratio . The amount is unknown, and the base is 24.

 

              24 • 110 = 100 •

 2,640 ÷ 100=

26.4 =

Cross multiply and solve for by dividing 2,640 by 100.

26.4 is 110% of 24.

 

18 is 125% of what number?

 

A) 0.144

B) 14.4

C) 22.5

D)  (or about 694.4)

 

Incorrect. You probably didn’t write a proportion and just divided 18 by 125. Or, you incorrectly set up one fraction as  and set this equal to the base, . The percent in this case is 125%, so one fraction in the proportion should be . The base is unknown and the amount is 18, so the other fraction is . Solving the proportion  gives = 14.4.

 

B) 14.4

Correct. The percent in this case is 125%, so one fraction in the proportion should be . The base is unknown and the amount is 18, so the other fraction is . Solving the proportion  gives = 14.4.

 

C) 22.5

Incorrect. You probably put the amount (18) over 100 in the proportion, rather than the percent (125). Perhaps you thought 18 was the percent and 125 was the base. The correct percent fraction for the proportion is . The base is unknown and the amount is 18, so the other fraction is . Solving the proportion  gives = 14.4.

 

D)  (or about 694.4)

Incorrect. You probably confused the amount (18) with the percent (125) when you set up the proportion. The correct percent fraction for the proportion is . The base is unknown and the amount is 18, so the other fraction is . Solving the proportion  gives = 14.4.

 

Let’s go back to the problem that was posed at the beginning. You can now solve this problem as shown in the following example.

Problem

 

How much is 15% of $220?

Simplify the problems by eliminating extra words.

 

     Percent: 15%

Base:  220

Amount:

Identify the percent, the base, and the amount.

 

15% · 220 =

Write the percent equation. Percent · Base = Amount

 

0.15 · 220  = 33

The coupon will take $33 off the original price.

You can estimate to see if the answer is reasonable. Since 15% is half way between 10% and 20%, find these numbers.

10% of 220 = 0.1 · 220 = 22

20% of 220 = 0.2 · 220 = 44

The answer, 33, is between 22 and 44. So $33 seems reasonable.

There are many other situations that involve percents. Below are just a few.

Problem

 

What number + 5% of that number is $31.50?

 

105% of what number = 31.50?

In this problem, you know that the tax of 5% is added onto the cost of the books. So if the cost of the books is 100%, the cost plus tax is 105%.

 

Percent: 105%

             Base:

Amount: 31.50

Identify the percent, the base, and the amount.

 

105% · = 31.50

Write the percent equation. Percent · Base = Amount.

 

1.05 · = 31.50

 

= 3.50 ÷ 1.05 = 30

Divide to undo the multiplication of times 1.05.

The books cost $30 before tax.

Problem

 

35 is what percent of 20?

Simplify the problem by eliminating extra words.

 

Percent:

                Base: 20

Amount: 35

Identify the percent, the base, and the amount.

 

· 20 = 35

Write the percent equation. Percent · Base = Amount.

 

= 35 ÷ 20

Divide to undo the multiplication of times 20.

 

= 1.75 = 175%

Since 35 is 175% of 20, Susana worked 75% more this week than she did last week. (You can think of this as “Susana worked 100% of the hours she worked last week, as well as 75% more.”)

Real Life Problems on Percentage

Real life problems on percentage will help us to solve different types of problems related to the real-life situations. To understand the procedures follow step-by-step explanation so that you can solve any other similar type of percentage problems.

Solved real life problems on percentage:

1.  Mike needs 30% to pass. If he scored 212 marks and falls short by 13 marks, what was the maximum marks he could have got?

If Mike had scored 13 marks more, he could have scored 30%

Therefore, Mike required 212 + 13 = 225 marks

Let the maximum marks be m.

Then 30 % of m = 225

(30/100) × m = 225

m = (225 × 100)/30

m = 22500/30

2. A number is increased by 40 % and then decreased by 40 %. Find the net increase or decrease per cent.

Solution:            

Let the number be 100.

Increase in the number = 40 % = 40 % of 100

                               = (40/100 × 100)

                               = 40

Therefore, increased number = 100 + 40 = 140

This number is decreased by 40 %

Therefore, decrease in number = 40 % of 140

                                             = (40/100 × 140)

                                             = 5600/100

                                             = 56

Therefore, new number = 140 - 56 = 84

Thus, net decreases = 100 - 84 = 16

Hence, net percentage decrease = (16/100 × 100) %

                                               = (1600/100) %

                                               = 16 %

3. Max scored 6 marks more than what he did in the previous examination in which he scored 30. Maria scored 30 marks more than she did in the previous examination in which she scored 60. Who showed less improvement?

Max percentage improvement in the first exam = (6/30 × 100) %

                                                                     = (600/30) %

                                                                     = 20 %

Maria percentage improvement in the first exam = (30/60 × 100) %

                                                                       = (3000/60) %

                                                                       = 50 %

Hence, 20 % < 50 %

Therefore, Max showed less improvement.

Fraction into Percentage

Percentage into Fraction

Percentage into Ratio

Ratio into Percentage

Percentage into Decimal

Decimal into Percentage

Percentage of the given Quantity

How much Percentage One Quantity is of Another?

Percentage of a Number

Increase Percentage

Decrease Percentage

Basic Problems on Percentage

Solved Examples on Percentage

Problems on Percentage

Word Problems on Percentage

Application of Percentage

8th Grade Math Practice From Real Life Problems on Percentage to HOME PAGE

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Solving problems with percentages

  • Price difference I
  • Price difference II
  • How many students?

To solve problems with percent we use the percent proportion shown in "Proportions and percent".

$$\frac{a}{b}=\frac{x}{100}$$

$$\frac{a}{{\color{red} {b}}}\cdot {\color{red} {b}}=\frac{x}{100}\cdot b$$

$$a=\frac{x}{100}\cdot b$$

x/100 is called the rate.

$$a=r\cdot b\Rightarrow Percent=Rate\cdot Base$$

Where the base is the original value and the percentage is the new value.

47% of the students in a class of 34 students has glasses or contacts. How many students in the class have either glasses or contacts?

$$a=r\cdot b$$

$$47\%=0.47a$$

$$=0.47\cdot 34$$

$$a=15.98\approx 16$$

16 of the students wear either glasses or contacts.

We often get reports about how much something has increased or decreased as a percent of change. The percent of change tells us how much something has changed in comparison to the original number. There are two different methods that we can use to find the percent of change.

The Mathplanet school has increased its student body from 150 students to 240 from last year. How big is the increase in percent?

We begin by subtracting the smaller number (the old value) from the greater number (the new value) to find the amount of change.

$$240-150=90$$

Then we find out how many percent this change corresponds to when compared to the original number of students

$$90=r\cdot 150$$

$$\frac{90}{150}=r$$

$$0.6=r= 60\%$$

We begin by finding the ratio between the old value (the original value) and the new value

$$percent\:of\:change=\frac{new\:value}{old\:value}=\frac{240}{150}=1.6$$

As you might remember 100% = 1. Since we have a percent of change that is bigger than 1 we know that we have an increase. To find out how big of an increase we've got we subtract 1 from 1.6.

$$1.6-1=0.6$$

$$0.6=60\%$$

As you can see both methods gave us the same answer which is that the student body has increased by 60%

Video lessons

A skirt cost $35 regulary in a shop. At a sale the price of the skirtreduces with 30%. How much will the skirt cost after the discount?

Solve "54 is 25% of what number?"

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Enter the value(s) for the required question and click the adjacent Go button.

PERCENTAGES

This section will explain how to apply algebra to percentage problems.

In algebra problems, percentages are usually written as decimals.

Example 1. Ethan got 80% of the questions correct on a test, and there were 55 questions. How many did he get right?

The number of questions correct is indicated by:

solving problems involving percents

Ethan got 44 questions correct.

Explanation: % means "per one hundred". So 80% means 80/100 = 0.80.

Example 2. A math teacher, Dr. Pi, computes a student’s grade for the course as follows:

solving problems involving percents

a. Compute Darrel's grade for the course if he has a 91 on the homework, 84 for his test average, and a 98 on the final exam.

solving problems involving percents

Darrel’s grade for the course is an 89.6, or a B+.

b. Suppose Selena has an 89 homework average and a 97 test average. What does Selena have to get on the final exam to get a 90 for the course?

The difference between Part a and Part b is that in Part b we don’t know Selena’s grade on the final exam.

So instead of multiplying 30% times a number, multiply 30% times E. E is the variable that represents what Selena has to get on the final exam to get a 90 for the course.

solving problems involving percents

Because Selena studied all semester, she only has to get a 79 on the final to get a 90 for the course.

Example 3. Sink Hardware store is having a 15% off sale. The sale price of a toilet is $97; find the retail price of the toilet.

a. Complete the table to find an equation relating the sale price to the retail price (the price before the sale).

Vocabulary: Retail price is the original price to the consumer or the price before the sale. Discount is how much the consumer saves, usually a percentage of the retail price. Sale Price is the retail price minus the discount.

solving problems involving percents

b. Simplify the equation.

solving problems involving percents

Explanation: The coefficient of R is one, so the arithmetic for combining like terms is 1 - 0.15 = .85. In other words, the sale price is 85% of the retail price.

c. Solve the equation when the sale price is $97.

solving problems involving percents

The retail price for the toilet was $114.12. (Note: the answer was rounded to the nearest cent.)

The following diagram is meant as a visualization of problem 3.

solving problems involving percents

The large rectangle represents the retail price. The retail price has two components, the sale price and the discount. So Retail Price = Sale Price + Discount If Discount is subtracted from both sides of the equation, a formula for Sale Price is found. Sale Price = Retail Price - Discount

Percentages play an integral role in our everyday lives, including computing discounts, calculating mortgages, savings, investments, and estimating final grades. When working with percentages, remember to write them as decimals, to create tables to derive equations, and to follow the proper procedures to solve equations.

Study Tip: Remember to use descriptive letters to describe the variables.

CHAPTER 1 REVIEW

This unit introduces algebra by examining similar models. You should be able to read a problem and create a table to find an equation that relates two variables. If you are given information about one of the variables, you should be able to use algebra to find the other variable.

Signed Numbers:

Informal Rules:

Adding or subtracting like signs: Add the two numbers and use the common sign.

solving problems involving percents

Adding or subtracting unlike signs: Subtract the two numbers and use the sign of the larger, (more precisely, the sign of the number whose absolute value is largest.)

solving problems involving percents

Multiplying or dividing like signs: The product or quotient of two numbers with like signs is always positive.

solving problems involving percents

Multiplying or dividing unlike signs: The product or quotient of two numbers with unlike signs is always negative.

solving problems involving percents

Order of operations: P lease E xcuse M y D ear A unt S ally 1. Inside P arentheses, (). 2. E xponents. 3. M ultiplication and D ivision (left to right) 4. A ddition and S ubtraction (left to right)

solving problems involving percents

Study Tip: All of these informal rules should be written on note cards.

Introduction to Variables:

Generate a table to find an equation that relates two variables.

Example 6. A car company charges $14.95 plus 35 cents per mile.

solving problems involving percents

Simplifying Algebraic Equations:

solving problems involving percents

Combine like terms:

solving problems involving percents

Solving Equations:

1. Simplify both sides of the equation. 2. Write the equation as a variable term equal to a constant. 3. Divide both sides by the coefficient or multiply by the reciprocal. 4. Three possible outcomes to solving an equation. a. One solution ( a conditional equation ) b. No solution ( a contradiction ) c. Every number is a solution (an identity )

solving problems involving percents

Applications of Linear Equations:

This section summarizes the major skills taught in this chapter.

Example 9. A cell phone company charges $12.50 plus 15 cents per minute after the first six minutes.

a. Create a table to find the equation that relates cost and minutes.

solving problems involving percents

c. If the call costs $23.50, how long were you on the phone?

solving problems involving percents

If the call costs $23.50, then you were on the phone for approximately 79 minutes.

Literal Equations:

A literal equation involves solving an equation for one of two variables.

solving problems involving percents

Percentages:

Write percentages as decimals.

Example 11. An English teacher computes his grades as follows:

solving problems involving percents

Sue has an 87 on the short essays and a 72 on the research paper. If she wants an 80 for the course, what grade does Sue have to get on the final?

solving problems involving percents

Sue has to get a 78.36 in the final exam to get an 80 for the course.

Study Tips:

1. Make sure you have done all of the homework exercises. 2. Practice the review test on the following pages by placing yourself under realistic exam conditions. 3. Find a quiet place and use a timer to simulate the test period. 4. Write your answers in your homework notebook. Make copies of the exam so you may then re-take it for extra practice. 5. Check your answers. 6. There is an additional exam available on the Beginning Algebra web page. 7. DO NOT wait until the night before the exam to study.

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Percentage Word Problems

Welcome to our Basic Percentage Word Problems. In this area, we have a selection of basic percentage problem worksheets designed for 6th grade students who are just starting to learn about percentages to help them to solve a range of simple percentage problems.

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Percentage Learning

Percentages are another area that children can find quite difficult. There are several key areas within percentages which need to be mastered in order.

Our selection of percentage worksheets will help you to find percentages of numbers and amounts, as well as working out percentage increases and decreases and converting percentages to fractions or decimals.

Key percentage facts:

  • 50% = 0.5 = ½
  • 25% = 0.25 = ¼
  • 75% = 0.75 = ¾
  • 10% = 0.1 = 1 ⁄ 10
  • 1% = 0.01 = 1 ⁄ 100

How to work out Percentages of a number

This page will help you learn to find the percentage of a given number.

There is also a percentage calculator on the page to support you work through practice questions.

  • Percentage Of Calculator

This is the calculator to use if you want to find a percentage of a number.

Simple choose your number and the percentage and the calculator will do the rest.

Percentage of Calculator image

Basic Percentage Word Problems

Here you will find a selection of worksheets on percentages designed to help your child practise how to apply their knowledge to solve a range of percentage problems..

The sheets are graded so that the easier ones are at the top.

The sheets have been split up into sections as follows:

  • spot the percentage problems where the aim is to use the given facts to find the missing percentage;
  • solving percentage of number problems, where the aim is to work out the percentage of a number.

Each of the sheets on this page has also been split into 3 different worksheets:

  • Sheet A which is set at an easier level;
  • Sheet B which is set at a medium level;
  • Sheet C which is set at a more advanced level for high attainers.

Spot the Percentages Problems

  • Spot the Percentage 1A
  • PDF version
  • Spot the Percentage 1B
  • Spot the Percentage 1C
  • Spot the Percentage 2A
  • Spot the Percentage 2B
  • Spot the Percentage 2C

Percentage of Number Word Problems

  • Percentage of Number Problems 1A
  • Percentage of Number Problems 1B
  • Percentage of Number Problems 1C
  • Percentage of Number Problems 2A
  • Percentage of Number Problems 2B
  • Percentage of Number Problems 2C
  • Percentage of Number Problems 3A
  • Percentage of Number Problems 3B
  • Percentage of Number Problems 3C

More Recommended Math Worksheets

Take a look at some more of our worksheets similar to these.

6th Grade Percentage Word Problems

The sheets in this area are at a harder level than those on this page.

The problems involve finding the percentage of numbers and amounts, as well as finding the amounts when the percentage is given.

  • 6th Grade Percent Word Problems
  • Percentage Increase and Decrease Worksheets

We have created a range of worksheets based around percentage increases and decreases.

Our worksheets include:

  • finding percentage change between two numbers;
  • finding a given percentage increase from an amount;
  • finding a given percentage decrease from an amount.

Percentage of Money Amounts

Often when we are studying percentages, we look at them in the context of money.

The sheets on this page are all about finding percentages of different amounts of money.

  • Money Percentage Worksheets

Percentage of Number Worksheets

If you would like some practice finding the percentage of a range of numbers, then try our Percentage Worksheets page.

You will find a range of worksheets starting with finding simple percentages such as 1%, 10% and 50% to finding much trickier ones.

  • Percentage of Numbers Worksheets

Converting Percentages to Fractions

To convert a fraction to a percentage follows on simply from converting a fraction to a decimal.

Simply divide the numerator by the denominator to give you the decimal form. Then multiply the result by 100 to change the decimal into a percentage.

The printable learning fraction page below contains more support, examples and practice converting fractions to decimals.

Convert fractions to percentages Picture

  • Converting Fractions to Percentages

Convert Percent to Fraction Image

  • Convert Percent to Fraction

Online Percentage Practice Zone

Our online percentage practice zone gives you a chance to practice finding percentages of a range of numbers.

You can choose your level of difficulty and test yourself with immediate feedback!

  • Online Percentage Practice
  • Ratio Part to Part Worksheets

These sheets are a great way to introduce ratio of one object to another using visual aids.

The sheets in this section are at a more basic level than those on this page.

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  • Percentage Calculator

Percentage calculator

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This calculator is a free online math tool that solves eight types of percentage problems . Just input the values into the sentence that best describes the problem involving percentages, and the calculator will generate a step-by-step solution.

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How to solve percentage problems?

This calculator solves eight different types of percenatge problems. We will use some examples to show each type.

Type 1: What is x % of y?

Example: What is 40% of 60?

Step1: Change the word of to multiplication sign.

40% of 60 = 40% * 60

Step2: Change 40% to decimal number by dividing 40% by 100 [40% = 40/100 = 0.4]

40% * 60 = 0.4 * 60 = 24

Type 2: x is what percent of y?

Example: 16 is what percent of 40?

Step1: Translate the words into an equation

16 is what percent of 40
16 = x $ \cdot $ 40

Step2: Solve for $ x $

Step3: Multiply x by 100% to convert the result to a percentage.

Type 3: Percentage increase

Example: Mark’s hourly salary is \$15. What is the percentage increase in the salary if it is raised to \$18?

To solve this problem, we apply the percentage increase formula :

After putting the initial amount to 15 and the final amount to 18, we get:

Type 4: Percentage decrease

Example: The workforce at a corporation decreased from 135 to 110 personnel. What is the percentage decrease in the number of employees?

To solve this problem we use percentage decrease formula :

After putting the initial amount to 135 and final amount to 110 we get:

Unit 3: Ratios and rates

About this unit.

Learn all about proportional relationships. How are they connected to ratios and rates? What do their graphs look like? What types of word problems can we solve with proportions?

Intro to ratios

  • Intro to ratios (Opens a modal)
  • Basic ratios (Opens a modal)
  • Part:whole ratios (Opens a modal)
  • Ratio review (Opens a modal)
  • Basic ratios Get 5 of 7 questions to level up!

Visualize ratios

  • Ratios with tape diagrams (Opens a modal)
  • Equivalent ratio word problems (Opens a modal)
  • Ratios and double number lines (Opens a modal)
  • Ratios with tape diagrams Get 3 of 4 questions to level up!
  • Equivalent ratios with equal groups Get 3 of 4 questions to level up!
  • Create double number lines Get 3 of 4 questions to level up!
  • Ratios with double number lines Get 3 of 4 questions to level up!
  • Relate double number lines and ratio tables Get 3 of 4 questions to level up!

Equivalent ratios

  • Ratio tables (Opens a modal)
  • Solving ratio problems with tables (Opens a modal)
  • Equivalent ratios (Opens a modal)
  • Equivalent ratios: recipe (Opens a modal)
  • Understanding equivalent ratios (Opens a modal)
  • Ratio tables Get 3 of 4 questions to level up!
  • Equivalent ratios Get 3 of 4 questions to level up!
  • Equivalent ratio word problems Get 3 of 4 questions to level up!
  • Equivalent ratios in the real world Get 3 of 4 questions to level up!
  • Understand equivalent ratios in the real world Get 3 of 4 questions to level up!

Ratio application

  • Ratios on coordinate plane (Opens a modal)
  • Ratios and measurement (Opens a modal)
  • Part to whole ratio word problem using tables (Opens a modal)
  • Ratios on coordinate plane Get 3 of 4 questions to level up!
  • Ratios and units of measurement Get 3 of 4 questions to level up!
  • Part-part-whole ratios Get 3 of 4 questions to level up!

Intro to rates

  • Intro to rates (Opens a modal)
  • Solving unit rate problem (Opens a modal)
  • Solving unit price problem (Opens a modal)
  • Rate problems (Opens a modal)
  • Comparing rates example (Opens a modal)
  • Rate review (Opens a modal)
  • Unit rates Get 5 of 7 questions to level up!
  • Rate problems Get 3 of 4 questions to level up!
  • Comparing rates Get 3 of 4 questions to level up!

IMAGES

  1. Percents

    solving problems involving percents

  2. Problem Solving with Percents Practice

    solving problems involving percents

  3. Solving Percent Problems (examples, solutions, worksheets, videos

    solving problems involving percents

  4. Percentages

    solving problems involving percents

  5. Solving Problems involving Percents: DIGITAL BOOM Cards + 20 Printable

    solving problems involving percents

  6. Solving Problems involving Percents: DIGITAL BOOM Cards + 20 Printable

    solving problems involving percents

VIDEO

  1. PERCENTS TRICK 🤯

  2. Solving a Percent Word Problem

  3. Solving PERCENT PROBLEMS using IS over OF

  4. PERCENTS TRICK 🤯

  5. Proportion Word Problems (involving batting averages)

  6. 8.1 Solving Percent Problems (Part 1)

COMMENTS

  1. 5.2.1: Solving Percent Problems

    Problems involving percents have any three quantities to work with: the percent, the amount, and the base. The percent has the percent symbol (%) or the word "percent." In the problem above, 15% is the percent off the purchase price. The base is the whole amount. In the problem above, the whole price of the guitar is $220, which is the base.

  2. Solving percent problems (video)

    25% is part of a whole 100%.*. *25% is 1/4 of 100%*. so, you know that (150) is 1/4 of the answer (100%) Add 150 - 4 times (Because we know that 25% X 4 = 100%) And that is equal to: (150 + 150 + 150 + 150) = *600. The method they used in the video is also correct, but i think that this one is easier, and will make it more simple to solve the ...

  3. Percentages

    In word problems involving percentages, remember that the sum of all parts of the whole is 100 % ‍ . For example, if a teacher has graded 60 % ‍ of an assignment, then they have not graded 100 − 60 % = 40 % ‍ of the assignment. 60 % ‍ and 40 % ‍ are complementary percentages: they add up to 100 % ‍ .

  4. Percent problems (practice)

    Percent problems. A brand of cereal had 1.2 milligrams ( mg) of iron per serving. Then they changed their recipe so they had 1.8 mg of iron per serving. What was the percent increase in iron? Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a ...

  5. 4.2: Percents Problems and Applications of Percent

    Solving Percent Problems: Percent Increase. When a quantity changes, it is often useful to know by what percent it changed. If the price of a candy bar is increased by \(50\) cents, you might be annoyed because it's it's a relatively large percentage of the original price. If the price of a car is increased by \(50\) cents, though, you ...

  6. How to Solve Percent Problems? (+FREE Worksheet!)

    How to Solve Simple Interest Problems; Step by step guide to solve percent problems . In each percent problem, we are looking for the base, or part or the percent. Use the following equations to find each missing section. Base \(= \color{black}{Part} \ ÷ \ \color{blue}{Percent}\) \(\color{ black }{Part} = \color{blue}{Percent} \ ×\) Base

  7. Solving Percent Problems (solutions, examples, worksheets, videos

    • Students find the percent of a quantity. • Given a part and the percent, students solve problems involving finding the whole. Lesson 29 Summary • Percent problems have three parts: whole, part, percent. • Percentage problems can be solved using models such as ratio tables, tape diagrams, double number line diagrams, and 10 x 10 rids ...

  8. Solving percent problems

    Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: https://www.khanacademy.org/math/cc-seventh-grade-math/cc-7th-fr...

  9. Different Types of Percentage Problems

    Now we will apply the concept of percentage to solve various real-life examples on percentage. Solved examples on percentage: 1. In an election, candidate A got 75% of the total valid votes. If 15% of the total votes were declared invalid and the total numbers of votes is 560000, find the number of valid vote polled in favour of candidate.

  10. Percentages Worksheets

    First, recognize that 2479 is less than 3700, so the percentage value must also be less than 100%. Divide 2479 by 3700 and multiply by 100. 2479 ÷ 3700 × 100 = 67%. Calculating the Percentage a Whole Number is of Another Whole Number. Calculating the Percentage a Whole Number is of Another Whole Number (Percents from 1% to 99%) Calculating ...

  11. Solving Percent Problems

    Problems involving percents have any three quantities to work with: the percent, the amount, and the base. The percent has the percent symbol (%) or the word "percent." In the problem above, 15% is the percent off the purchase price. The base is the whole amount. In the problem above, the whole price of the guitar is $220, which is the base.

  12. Real Life Problems on Percentage

    Solved real life problems on percentage: 1. Mike needs 30% to pass. If he scored 212 marks and falls short by 13 marks, what was the maximum marks he could have got? Solution: If Mike had scored 13 marks more, he could have scored 30%. Therefore, Mike required 212 + 13 = 225 marks. Let the maximum marks be m.

  13. Solving problems with percentages (Pre-Algebra, Ratios and percent

    To solve problems with percent we use the percent proportion shown in "Proportions and percent". a b = x 100 a b = x 100. a b ⋅b = x 100 ⋅ b a b ⋅ b = x 100 ⋅ b. a = x 100 ⋅ b a = x 100 ⋅ b. x/100 is called the rate. a = r ⋅ b ⇒ Percent = Rate ⋅ Base a = r ⋅ b ⇒ P e r c e n t = R a t e ⋅ B a s e. Where the base is the ...

  14. Solving Problems Involving Percent Increase and Decrease

    Rearrange the formula percent = part whole to solve problems involving percentages. A value of 1 can represent 100%. Values lower than 1 correspond to a percent decrease while values greater than 1 correspond to a percent increase. For example, a 20% off discount means the price will only be 80% of the original cost.

  15. Calculate percentages with Step-by-Step Math Problem Solver

    A math teacher, Dr. Pi, computes a student's grade for the course as follows: a. Compute Darrel's grade for the course if he has a 91 on the homework, 84 for his test average, and a 98 on the final exam. Wrote percents as decimals. G = 18.2 + 42 + 29.4 Multiplied G = 89.6 Added. Darrel's grade for the course is an 89.6, or a B+. b.

  16. Multi-step ratio and percent problems (article)

    In other words, 150/20 is 7.5 so we already have half of the ratio (The answer must be an equivalent ratio to 3 : 20). __:150. To get the last half of the answer, we must multiply 7.5 by 3 because we already found out that 150/20 is 7.5. 3 x 7.5 is 22.5 so the answer is 22.5 : 150. Hope this helps!

  17. Basic Percentage Word Problems

    Our selection of percentage worksheets will help you to find percentages of numbers and amounts, as well as working out percentage increases and decreases and converting percentages to fractions or decimals. Key percentage facts: 50% = 0.5 = ½. 25% = 0.25 = ¼. 75% = 0.75 = ¾.

  18. PDF Percent Equation P B A

    Percent Proportion. Problems involving the percent equation can also be solved with the proportion: Percent Amount (is) =. 100 Base (of) When the percent is given, drop the percent sign and place the percent over 100. Cross multiply to solve the proportion. Example 2: 27 is 45% of what number?

  19. Percentage Calculator with all steps

    This calculator is a free online math tool that solves eight types of percentage problems.Just input the values into the sentence that best describes the problem involving percentages, and the calculator will generate a step-by-step solution.

  20. Percent word problems (practice)

    Percent word problem: recycling cans. Video 3 minutes 4 seconds 3:04. Finding the whole with a tape diagram. Video 2 minutes 7 seconds 2:07. Percent of a whole number. ... Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the ...

  21. Percent Given Value Calculator

    The resulting percentage, a 20% increase, will be displayed. 3. Determining the Whole Value from a Given Percentage: A Percent Calculator also comes in handy when one has to find the whole value (W) corresponding to a given percentage (P) and a part of that whole value (PV). It helps in reverse computing the amount or quantity as required.

  22. Ratios and rates

    Percent & rational number word problems. Unit 9. Proportional relationships. Unit 10. One-step and two-step equations & inequalities. Unit 11. Roots, exponents, & scientific notation. ... Solving ratio problems with tables (Opens a modal) Equivalent ratios (Opens a modal) Equivalent ratios: recipe (Opens a modal)