# Lesson 10What Are Percentages?

Let’s learn about percentages.

### Learning Targets:

• I can create a double number line with percentages on one line and dollar amounts on the other line.
• I can explain the meaning of percentages using dollars and cents as an example.

## 10.1Dollars and Cents

Find each answer mentally.

1. A sticker costs 25 cents. How many dollars is that?
2. A pen costs 1.50 dollars. How many cents is that?
3. How many cents are in one dollar?
4. How many dollars are in one cent?

## 10.2Coins

1. Complete the table to show the values of these U.S. coins.

 coin value (cents) penny nickel dime quarter half dollar dollar

The value of a quarter is 25% of the value of a dollar because there are 25 cents for every 100 cents.

2. Write the name of the coin that matches each expression.

1. 25% of a dollar
2. 5% of a dollar
1. 1% of a dollar
2. 100% of a dollar
1. 10% of a dollar
2. 50% of a dollar
1. The value of 6 dimes is what percent of the value of a dollar?
1. The value of 6 quarters is what percent of the value of a dollar?

### Are you ready for more?

Find two different sets of coins that each make 120% of a dollar, where no type of coin is in both sets.

A $1 coin is worth 100% of the value of a dollar. Here is a double number line that shows this. 1. The coins in Jada’s pocket are worth 75% of a dollar. How much are they worth (in dollars)? 2. The coins in Diego’s pocket are worth 150% of a dollar. How much are they worth (in dollars)? 1. Elena has 3 quarters and 5 dimes. What percentage of a dollar does she have? ## Lesson 10 Summary A percentage is a rate per 100. We can find percentages of$10 using a double number line where 10 and 100% are aligned, as shown here:

Looking at the double number line, we can see that $5.00 is 50% of$10.00 and that $12.50 is 125% of$10.00.

## Glossary Terms

percent

The word percent means “for each 100.” The symbol for percent is %.

For example, a quarter is worth 25 cents, and a dollar is worth 100 cents. We can say that a quarter is worth 25% of a dollar.

percentage

A percentage is a rate per 100.

For example, a fish tank can hold 36 liters. Right now there is 27 liters of water in the tank. The percentage of the tank that is full is 75%.

## Lesson 10 Practice Problems

1. What percentage of a dollar is the value of each coin combination?

1. 4 dimes
2. 1 nickel and 3 pennies
3. 5 quarters and 1 dime
1. List three different combinations of coins, each with a value of 30% of a dollar.

2. List two different combinations of coins, each with a value of 140% of a dollar.

2. The United States government used to make coins of many different values. For each coin, state its worth as a percentage of $1. 1. cent 2. 3 cents 1. 20 cents 1.$5
3. Complete the double number to line show percentages of $50. 4. Elena bought 8 tokens for$4.40. At this rate:

1. How many tokens could she buy with $6.05? 2. How much do 19 tokens cost? 5. A snail travels 10 cm in 4 minutes. At this rate: 1. How long will it take the snail to travel 24 cm? 2. How far does the snail travel in 6 minutes? 1. 3 tacos cost$18. Complete the table to show the cost of 4, 5, and 6 tacos at the same rate.
number of tacos cost in dollars rate in dollars per taco
3 18
4
5
6

b. If you buy tacos for dollars, what is the unit rate?