# Using Ratios to Solve Problems

## Overview

## Using Ratios to Solve Problems

We can use what we know about ratios to find percentages. A percent is simply a

rate per **100**.

Let’s look at an example.

Approximately 8 out of every 25 people are overweight in the United States. What

percentage of people are overweight in the U.S.?

To solve the problem, we first need to determine the ratio, which is **8 : 25**.

Next, we need to determine how many people out of 100 are overweight.

.32 x 100 = 32% (Percent)

We multiply by **100** because a percent represents a rate per **100**.

Approximately **32%** of people are overweight in the United States.

**What if the problem asks you to convert a percent to a number?**

Taylor has **50** books on her bookshelf. **20%** of the books are nonfiction. How many

books are nonfiction?

We need to multiply **20%** by **50**. Remember, percent means per **100**.

So **20%** =

Taylor has 10 nonfiction books on her bookshelf.

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###
The rectangle below represents one whole. What percent of the rectangle is shaded?

Answer
30%

3 out of 10 squares are shaded. = 0.3 x 100 = 30

The rectangle below represents one whole. What percent of the rectangle is shaded?

30%

3 out of 10 squares are shaded.

###
The rectangle below represents one whole.

What percent of the rectangle is shaded?

Answer
50%

5 out of 10 squares are shaded. = 0.5 x 100 = 50

The rectangle below represents one whole.

What percent of the rectangle is shaded?

50%

5 out of 10 squares are shaded.

###
The rectangle below represents one whole.

What percent of the rectangle is shaded?

Answer
60%

6 out of 10 squares are shaded. = 0.6 x 100 = 60

The rectangle below represents one whole.

What percent of the rectangle is shaded?

60%

6 out of 10 squares are shaded.

###
The rectangle below represents one whole.

What percent of the rectangle is shaded?

Answer
5%

5 out of 100 squares are shaded. is 5%

The rectangle below represents one whole.

What percent of the rectangle is shaded?

5%

5 out of 100 squares are shaded.

###
The rectangle below represents one whole.

What percent of the rectangle is shaded?

Answer
30%

30 out of 100 squares are shaded. is 30%

The rectangle below represents one whole.

What percent of the rectangle is shaded?

30%

30 out of 100 squares are shaded.

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