Percent: a ratio of a number to 100 (per-cent = ‘per one ...



Percent: a ratio of a number to 100 (per-cent = ‘per one hundred’)

Ex. 8% means “8 per hundred,” or “8 out of 100.” (8/100)

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”. (Think of money…$1.00 is considered 100%, or all)

0% 25% 50% 75% 100%

0 1/4 1/2 3/4 1/1

0 .25 .50 .75 1

Recognizing Percent Shaded:

What is the percent that is shaded?

• We know that it is less than 50% because it is a little less than half shaded. However, it is more than 25% shaded. The answer would be close to 35%.

•

Writing percents as fractions in simplest form:

Ex. 40% = 40 40 ÷ 20 = 2

100 100 ÷ 20 = 5

Ex. Up to 55% of the heat lost by your body can be lost through your

head. Write 55% as a fraction in simplest form.

55% = 55 ÷ 5 = 11

100 ÷ 5 = 20

Changing PERCENT to DECIMAL

• Remove the percent sign and move the decimal two places to the LEFT

Ex. 62% = .62

Ex. 145% = 1.45

Changing DECIMAL to PERCENT

• Move the decimal two places to the RIGHT and put a % sign

Ex. .09 = 9%

Ex. 10.784 = 1078.4%

Ex. .7 = 70%

Fraction to Percent

• When changing a fraction to a percent, multiply the fraction by 100.

o Ex. 7 7 · 100 = 700 = 35

20 20 1 20 1

So…7/20 is 35%

Comparing Fractions/Decimals/and Percents

• When comparing fractions, decimals, and percents, change all numbers to decimals. (It’s the easiest way)

o Ex. 6/9 75% .72

6 ÷ 9 = .67 75% = .75 .72 = .72

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