pre-algebra. lesson 6-4 warm-up pre-algebra what is “percent”? how do you write a percent as a...

$: PRE-ALGEBRA. Lesson 6-4 Warm-Up PRE-ALGEBRA What is “percent”? How do you write a percent as a fraction or a decimal? percent: a ratio that compares$
PRE-ALGEBRA

PRE-ALGEBRA

Lesson 6-4 Warm-Up

PRE-ALGEBRA

What is “percent”?

How do you write a percent as a fraction or a decimal?

percent: a ratio that compares a number to 100

To write a percent as a fraction, make the numerator the percent and the denominator 100 (“out of 100”). Then, simplify the fraction. To write a percent as a decimal: turn it into a fraction first (then you can turn the fraction into a decimal by dividing) or simply move the decimal two places to the left.

Example:The following model shows 41 out of 100 squares shaded, or 41% of the big square shaded.

Example:Write 125% each percent as a fraction and a decimal.

Write as a fraction with a denominator of 100.

Then, simplify the fraction.

Write the improper fraction as a mixed number.

Divide the numerator by the denominator to change a fraction into a decimal.

Fractions, Decimals, and Percents (6-4)

125100

2525

= 54

54

14= 1

5 4 = 1.25

PRE-ALGEBRA

Write each percent as a fraction or a mixed number.

a. 30%

b. 175%

Write as a fraction with a denominator of 100.30

100

Simplify.3

10

Write as a fraction with a denominator of 100.175100

1 Write as a mixed number.34

Simplify.74

Fractions, Decimals, and PercentsLESSON 6-4

Additional Examples

PRE-ALGEBRA

Express 7.3% as a decimal.

= 0.073

7.3% = Write as a fraction with a denominator of 100.7.3100

= 007.3 Divide by moving the decimal point left two places.You may need to write one or more zeros.


Additional Examples

PRE-ALGEBRA


(7-1)

How do you write a fraction as a percent?

To write a fraction as a percent, find an equal fraction with a denominator of 100 (if the denominator is 100, the numerator will always be the percent, since percent means “out of 100”) or make a proportion and use cross products.Example: According to the school cafeteria, 6 out of 25 students bring their lunch to school. What percent of the students bring their lunches to school?

Method 1: Proportion

# %

Known (Part) 6 x

Unknown (Whole) 25 100

= Proportion .6

25x

100

25 • x = 6 • 100 Cross products are equal.

25x = 600 Simplify.

= Divide both sides by 25. .25x25

60025

x = 24 Simplify.

24% of the students bring their lunches..

1

1

24

1

PRE-ALGEBRA

How do you write a fraction as a percent?

Method 2: Equal Fractions

= Write an equal fraction with a denominator of 100 (since percents have 100 in the denominator.

625 100

= Multiply the numerator by the same number that you multiply the denominator by to find the equivalent fraction with a denominator of 100.

625

24100

4

4

24% of the students bring their lunches..


PRE-ALGEBRA

Write as a percent.7

20

= Find the fraction with denominator 100

that is equal to .

720

35100

5

5

720

720 = Write a proportion. Percents have

100 in the denominator.

p100

720 = = 35% Write using a percent symbol.35

100


Additional Examples

PRE-ALGEBRA

Four out of seven members of the chess club won a game at the district tournament. What percent of the chess club members won a game?

0.5714 Divide the numerator by the denominator.

57.14% Write as a percent.

About 57% of the chess club members won a game.

Write a fraction.47


Additional Examples

PRE-ALGEBRA

“Fractions, Decimals, and Percents” (6-4)

(7-1)How do you write a decimal as a percent?

To write a decimal as a percent, write the decimal as a fraction and change the fraction into a percent using proportions or equal fractions or move the decimal two places to the right.

Method 1: Change the decimal to a fraction

Example: Write 0.076 as a percent.

Method 2: Move the decimal 2 places to the right.

0.076 = Write the decimal as a fraction the way you read it.

761000

0.076 = 7.6%

= Divide the numerator by the same number that you divide the denominator by to find the equivalent fraction with a denominator of 100.

761000

7.6100

10

10

0. 0 7 6 Jump the decimal two places to the right.

= 7 . 6 %

PRE-ALGEBRA

Write each decimal as a percent.

a. 0.16

b. 0.03

0.16 = 16100 Write the decimal as a fraction.

= 16% Write as a percent.

0.03 = 3100 Write the decimal as a fraction.

= 3% Write as a percent.


Additional Examples

PRE-ALGEBRA

Express 0.412 as a percent.

Method 1 Rewrite as a fraction.

= 41.2%

Method 2 Move the decimal point.

0.412 = 41.2%

0.412 = 4121,000

= 412 ÷ 101,000 ÷ 10

= 41.2100


Additional Examples

PRE-ALGEBRA

Write each percent as a fraction or mixed number, and as a decimal.

1. 325% 2. 1.1%

Write each as a percent.

3. 2.01 4.

5. Six out of fifteen students own skateboards. What percent of students own skateboards?

134

, or 3 ; 3.2514

111,000

; or 0.011

201%

35

60%

40%

Lesson Quiz


pre-algebra. lesson 6-4 warm-up pre-algebra what is “percent”? how do you write a percent as a...

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