7-7 Percents

Warm UpWarm Up

Lesson Presentation

Problem of the Day

Lesson Quizzes

7-7 Percents

Warm UpWrite each fraction as a decimal.

1. 2.

Write each decimal as a fraction.

3. 0.375 4. 0.05

0.75 0.934__ 9

10 __

38__ 1

20 __

7-7 Percents

Problem of the Day

Wally wanted to change the scale of a drawing from 1 in. = 2 ft to 1 in. = 10 ft. The scale height of a building in the first drawing is 25 in. How high is the building in the new drawing?5 in.

7-7 Percents

Learn to write percents as decimals and as fractions.

7-7 Percents

Vocabulary

percent

7-7 Percents

Most states charge sales tax on items you purchase. Sales tax is a percent of the item’s price. A percent is a ratio of a number to 100.

You can remember that percent means “per hundred.” For example, 8% means “8 per hundred,” or “8 out of 100.”

7-7 Percents

If a sales tax rate is 8%, the following statements are true:

• For every $1.00 you spend, you pay $0.08 in sales tax.

• For every $10.00 you spend, you pay $0.80 in sales tax.

• For every $100 you spend, you pay $8 in sales tax.

Because percent means “per hundred,” 100% means “100 out of 100.” This is why 100% is often used to mean “all” or “the whole thing.”

7-7 Percents

Additional Example 1: Modeling Percent

Use a 10-by-10-square grid to model 17%.

A 10-by-10 square grid has 100 squares.

17% means “17 out of 100”

or .

Shade 17 squares out of 100 squares.

17100

___

7-7 Percents

Check It Out: Example 1

Use a 10-by-10-square grid to model 26%.

A 10-by-10 square grid has 100 squares.

26% means “26 out of 100”

or .

Shade 26 squares out of 100 squares.

26100

___

7-7 Percents

Additional Example 2: Writing Percents as Fractions

Write 35% as a fraction in simplest form.

Write the percent as a fraction with a denominator of 100.

Write the fraction in simplest form.

35% = 35100

___

35 ÷ 5100 ÷ 5

_______ = 720 __

Written as a fraction, 35% is . 720 __

7-7 Percents

Check It Out: Example 2

Write 65% as a fraction in simplest form.

Write the percent as a fraction with a denominator of 100.

Write the fraction in simplest form.

65% = 65100

___

65 ÷ 5100 ÷ 5

_______ = 1320

__

Written as a fraction, 65% is . 1320 __

7-7 Percents

Additional Example 3: Life Science Application

Janell has 20% body fat. Write 20% as a fraction in simplest form.

Write the percent as a fraction with a denominator of 100.

Write the fraction in simplest form.

20% = 20100

___

20 ÷ 20100 ÷ 20

_______ = 1 5 __

Written as a fraction, 20% is . 1 5 __

7-7 Percents

Check It Out: Example 3

Timmy has 14% body fat. Write 14% as a fraction in simplest form .

Write the percent as a fraction with a denominator of 100.

Write the fraction in simplest form.

14% = 14100

___

14 ÷ 2100 ÷ 2

_______ = 750

__

Written as a fraction, 14% is . 750 __

7-7 Percents

Additional Example 4: Writing Percents as Decimals

Write 56% as a decimal.

Write the percent as a fraction with a denominator of 100.

Write the fraction as a decimal.

56% = 56100

___

Written as a decimal, 56% is 0.56.

100 56.000.56

–500 600

–6000

To divide by 100, move the decimal point two places to the left. 56 ÷ 100 = 0.56

Remember!

7-7 Percents

Check It Out: Example 4

Write 32% as a decimal.

Write the percent as a fraction with a denominator of 100.

Write the fraction as a decimal.

32% = 32100

___

Written as a decimal, 32% is 0.32.

100 32.000.32

–300 200

–2000

7-7 Percents

Additional Example 5: Application

Water made up 85% of the fluids that Kirk drank yesterday. Write 85% as a decimal.

Write the percent as a fraction with a denominator of 100.

Write the fraction as a decimal.

85% = 85100

___

85 ÷ 100 = 0.85

Written as a decimal, 85% is 0.85.

7-7 Percents

Check It Out: Example 5

Water made up 95% of the fluids that Lisa drank yesterday. Write 95% as a decimal.

Write the percent as a fraction with a denominator of 100.

Write the fraction as a decimal.

95% = 95100

___

95 ÷ 100 = 0.95

Written as a decimal, 95% is 0.95.

7-7 Percents

Standard Lesson Quiz

Lesson Quizzes

Lesson Quiz for Student Response Systems

7-7 Percents

Lesson Quiz

Write each percent as a fraction in simplest form.

1. 52% 2. 29%

Write each percent as a decimal.

3. 17% 4. 86%

5. A store clerk has an 8% sales increase. Write

the increase as a fraction in simplest form and as

a decimal.

, 0.08

1325 __ 29

100 ___

0.17 0.86

225 __

7-7 Percents

1. Which of the following represents 15% as a fraction in simplest form?

A. B.

C. D.

Lesson Quiz for Student Response Systems

7-7 Percents

2. Which of the following represents 79% as a fraction in simplest form?

A. B.

C. D.

Lesson Quiz for Student Response Systems

7-7 Percents

3. Which of the following represents 26% as a decimal?

A. 2.6 B. 0.026

C. 0.26 D. 0.0026

Lesson Quiz for Student Response Systems

7-7 Percents

4. Which of the following represents 71% as a decimal?

A. 71 B. 0.71

C. 7.1 D. 0.071

Lesson Quiz for Student Response Systems

7-7 Percents

5. 82% of Brett’s DVD collection are action movies. Which of the following represents 82% as a fraction in simplest form and as a decimal?

A. B.

C. D.

Lesson Quiz for Student Response Systems