CHAPTER 7: RELATING FRACTIONS, DECIMALS, AND PERCENTS - BC

[Pages:19]CHAPTER 7: RELATING FRACTIONS, DECIMALS, AND PERCENTS

7.1 CONVERTING FRACTIONS TO DECIMALS P. 2-3 7.2 CONVERTING DECIMALS TO FRACTIONS P. 4-5 7.3 CONVERTING DECIMALS AND PERCENTS P. 6-7 7.4 CONVERSIONS REVIEW P. 8-9 7.5 THE PERCENT CIRCLE P. 10-11 7.6 FINDING THE PART P. 12-13 7.7 FINDING THE WHOLE P. 14-15 7.8 FINDING THE PERCENT P. 16-17 ANSWER KEY P. 18-19

7.1 CONVERTING FRACTIONS TO DECIMALS

Key Vocabulary 7.1

Repeating decimals: _______________________________________________________

Rational numbers: _________________________________________________________

Think 7.1

Divide the numerator by the denominator. a b a b

Add a decimal after the dividend and at least one zero. b a.0

Add at least 2 additional zeros to dividend until it divides evenly or until you get a repeating pattern.

2

5

0.4 2.0

5

2 0

0

1

4

0.25 1.0 0

4

8

20

20

0

0.33 1 or 0.33 1 3 1.00 3 3

9 10

9

0

Try It 7.1 Divide to convert the fractions to decimals

1) 3 _____ 4 2 _____

4) 3

2)

1 _____

8

3 _____ 5) 10

3 _____ 3) 5

7 _____ 6) 8

7.1 Practice Exercises

Divide to convert the fractions to decimals. 1) 1 _____ 4 2) 3 _____ 8 3) 7 _____ 10 4) 5 _____ 6 5) 1 _____ 2 6) 3 _____ 9 7) 1 _____ 6 8) 3 _____ 5 Tanner spent of his time at work stocking shelves and of the time with customers. 9) Write the amount of time Tanner spent stocking shelves as a decimal: _____

10) Write the amount of time Tanner spent with customers as a decimal: _____

7.2 Converting Decimals to Fractions

Think 7.2

To convert decimals to fractions, you need to write the decimal in fraction form. Simplify the fraction by reducing to lowest terms.

0.6 6 2 3 10 2 5

0.25 25 25 1 100 25 4

0.275 275 25 11 1, 000 25 40

For repeating fraction decimals, exclude the decimal and use just the fraction. 0.33or 3 3 1 1 33

Try It 7.2 Write each decimal as a fraction simplify by reducing the fraction to lowest terms. 1) 0.4 = _____ 2) 0.8 = _____ 3) 0.45 = _____ 4) 0.55 = _____ 5) 0.125 = _____ 6) 0.075 = _____

7.2 Practice Exercises

Write each decimal as a fraction simplify by reducing the fraction to lowest terms.

Decimal Form Fraction Form Simplify Fraction

1) 0.5 =

_________

_________

2) 0.2 =

_________

_________

3) 0.15 =

_________

_________

4) 0.35 =

_________

_________

5) 0.70 =

_________

_________

6) 0.075 =

_________

_________

7) 0.220 =

_________

_________

8) 0.375 =

_________

_________

9) 0.0025 =

_________

_________

10) Phillip walked 0.35 miles on Monday and 0.25 miles on Tuesday. Write the total

distance he walked as a fraction. _____________

7.3 CONVERTING DECIMALS AND PERCENTS

Key Vocabulary 7.3 Percent: _______________________________________________________________

Think 7.3

To convert a decimal to a percent, multiply the decimal by 100. Move the decimal 2 places right. Be sure to add zero placeholders as needed.

Drop the decimal, & add a percent sign.

(0.25) 0.2 5 x100 25%

(added zero) (0.5) 0.50 x 100 50%

(0.33 1) 0.33 1 x100 33 1 % (1.25) 1.25 x100 125%

33

3

To convert a percent to a decimal, divide the number by 100 (move the decimal 2 places

to the left.

Add zeros as needed, drop the percent sign and add a decimal.

(25%) 25% 100 0.25 (50%) 50% 100 0.5

(33 1 %) 33 1 % 100 .33 1 (5%) 05% 100 0.05

3

3

3

(added zero)

Try It 7.3 Convert the percent to decimal.

1) 35% = _________

2) 8 % = __________

3)

66 2 % = ________

3

4) 18% = __________

5) 80% = __________

6) 120% __________

7.3 Practice Exercises

Convert each decimal to a percent.

1) 0.3 = _____ % 2) 0.05 = _____ % 3) 0.45 = _____ % 4) 0.025 = _____ % 5) 2.45 = _____ %

Convert each percent to a decimal.

6) 3% = _____ 7) 15% = _____ 8) 90% = _____ 9) 160% = _____ 10) Jake ate 30% of his pizza for lunch. Write the amount he ate as a decimal. ____

7.4 CONVERTING FRACTIONS, DECIMALS, AND PERCENTS

Think 7.4 Fraction Decimal Percent (Simplify the fraction first as needed.) 0.4 2 0 2 5 2.0 0.4 x 100 40% 50 5

Percent Decimal Fraction (Simplify fraction as needed.) 3 5% 0 35 5 7

100 5 20

Try It 7.4

Convert the numbers and simplify. Fraction Decimal Percent (Simplify the fraction first as needed.)

1) 4 10

2) _____

3) _____

Percent 4) 60%

Decimal 5) _____

Fraction (Simplify fraction as needed.) 6) _____

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