# Lesson 10

What Are Percentages?

Let’s learn about percentages.

### 10.1: Dollars 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?

### 10.2: Coins

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.

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

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)? 3. Elena has 3 quarters and 5 dimes. What percentage of a dollar does she have? ### 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 Entries

• 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%.