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8-7 Percents

6th Grade Math HOMEWORK

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Our Learning Goal for Chapter 8Students will understand ratios, proportions, and percents by being able to write ratios, find unit rates, solve proportions, identify similar figures, find unknown measures, make scale drawings, understand relationships, and solve problems including those involving discounts, tips, sales tax, and simple interest.

Our Learning Goal Assignments• Learn to write ratios and rates and to find unit rates (8-1)• Learn to write and solve proportions (8-2)• Learn to use proportions to make conversions within the

customary system (8-3)• Learn to use ratios to identify similar figures (8-4)• Learn to use proportions and similar figures to find unknown

measures (8-5)• Learn to read and use map scale and scale drawings (8-6)• Learn to write percents as decimals and as fractions (8-7)• Learn to write decimals and fractions as percents (8-8)• Learn to find the missing value in a percent problem (8-9)• Learn to solve percent problems that involve discounts, tips,

and sales tax (8-10)

8-7 Percents

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Warm UpWarm Up

Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

Warm UpWrite each fraction as a decimal.

1. 2.

Write each decimal as a fraction.3. 0.375 4. 0.05

0.75 0.9

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8-7 Percents

34__ 9

10 __

38__ 1

20 __

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.

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8-7 Percents

Today’s Learning Goal Assignment

Learn to write percents as decimals and as fractions.

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8-7 Percents

Vocabulary

percent

Insert Lesson Title Here

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8-7 Percents

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8-7 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.”

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8-7 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.”

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8-7 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

___

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8-7 Percents

Try This: 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

___

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8-7 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 __

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8-7 Percents

Try This: 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 __

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8-7 Percents

Additional Example 3: Life Science Application

Janell is an ice skater with 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 __

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8-7 Percents

Try This: Example 3

Timmy is a football player with 10% body fat. Write 10% as a fraction in simplest form .

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

Write the fraction in simplest form.

10% = 10100

___

10 ÷ 10100 ÷ 10

_______ = 110

__

Written as a fraction, 10% is . 110 __

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8-7 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 fraction, 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!

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8-7 Percents

Try This: 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 fraction, 32% is 0.32.

100 32.000.32

–300 200

–2000

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8-7 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.

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8-7 Percents

Try This: 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.

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.

Insert Lesson Title Here

, 0.08

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8-7 Percents

1325 __ 29

100 ___

0.17 0.86

225 __