holt ca course 1 6-2 fractions, decimals, and percents preparation for ns1.4 calculate given...

Holt CA Course 1

6-2 Fractions, Decimals, and Percents

Preparation for NS1.4 Calculate given percentages of quantities and solve problems involving discounts at sales, interest earned, and tips.

California Standards

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Vocabulary:

Fraction to Decimal to Percent

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A group of students plan to collect 2,000 cans of food for a food bank. After 10 days, they have 800 cans of food.

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0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000

0 15

25

35

45

55

0 0.2 0.4 0.6 0.8 1.0

0 20% 40% 60% 80% 100%

The model shows that 800 out of 2,000 can be written as , , 0.4, or 40%. The students have reached 40% of their goal.

8002000

25

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Write 0.7 as a percent.

Teacher Example 1: Writing Decimals as Percents

Method 1: Use pencil and paper.

0.7 = 70100

= 70%

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

Write the numerator with a percent sign.

710

=

Method 2: Use mental math.

0.70 =

= 70%

Move the decimal point two places to the right and add a percent sign.

70.0%

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Write 0.3 as a percent.

Student Practice 1:


0.3 = 30100

= 30%

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


310

=


0.30 =

= 30%

Move the decimal point two places to the right and add a percent sign.

30.0%

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Write as a percent.58

58

= 5 ÷ 8

= 0.625

= 62.5%

Use division to write the fraction as a decimal.

Write the decimal as a percent.

Teacher Example 2: Writing Fractions as Decimals


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5 12.5 8 12.5

Write an equivalent fraction with a denominator of 100.

=


Teacher Example 2 Continued:


62.5 100

Write the numerator with a percent sign.= 62.5%

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35

= 3 ÷ 5

= 0.60

= 60%

Use division to write the fraction as a decimal.


Student Practice 2:


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3 20 5 20

Write an equivalent fraction with a denominator of 100.

=


Student Practice 2 Continued:


60 100

Write the numerator with a percent sign.= 60%

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27 out of 50 = Set up a ratio.


Teacher Example 3: Data Analysis Application

If 27 out of 50 people surveyed have the newspaper delivered to their home, what percent of these people have the newspaper delivered to their home?

2750

= 0.54

= 54%

54% of the people have the newspaper delivered to their home.

= 27 ÷ 50 Use division to write the fraction as a decimal.

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Check Use estimation to check that the answer is reasonable.

Teacher Example 3 Continued:

Because 50% is close to 54%, the answer is reasonable.

2750

≈ , or 50%2550

≈ 12

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11 out of 50 =


Student Practice 3:

If 11 out of 50 students surveyed have blue backpacks, what percent of the students have blue backpacks?

1150

= 22%

22% of the students have blue backpacks.

22100

=

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Check Use estimation to check that the answer is reasonable.

Student Practice 3 Continued:

Because 20% is close to 22%, the answer is reasonable.

22100

≈ , or 20%20100

≈ 15

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Lesson Quiz

60%

1. Write 0.65 as a percent.

2. Write as a percent. 610

65%

45%

3. If 36 out of 80 people surveyed have been on a boat, what percent of these people have been on a boat?

holt ca course 1 6-2 fractions, decimals, and percents preparation for ns1.4 calculate given...

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