NOTES 3.7 – PERCENTS

Step 1 - Place the percent over ______.

Step 2 - ________ the fraction to a proper fraction or mixed numeral in lowest terms.

CHANGING A PERCENT TO A FRACTION

100

REDUCE

Example 1 - Change 20% to a fraction

  20% =

 

Example 2 - Change 125% to a fraction

  125% =

100

1

5

100

1

1 4

20

125

Step 1 - Change the ___________ to a __________.

(Divide the numerator by the denominator)

 Step 2 - Move the decimal point ____ places to the _______.

CHANGING A FRACTION TO A PERCENT

FRACTION DECIMAL

RIGHT2

Example 3 - Change to a percent.

  = __________ = __________%

712

712 0.583 58.3

Step 1 - Move the decimal point _____ places to the _________.

Example 4 - Change 0.815 to a percent

 

0.815 = _______%

CHANGING A DECIMAL TO A PERCENT

81.5

RIGHT2

Step 1 - Move the decimal point ____ places to the _______.

(If there is no decimal point, it goes at the right of the last number in the percent)

Example 5 - Change 315% to a decimal

 

315% = ________

CHANGING A PERCENT TO A DECIMAL

3.15

LEFT2

EVERY percent problem has an ___, an ____, and a percent in it. Since percent means “PER HUNDRED” we can solve every percent problem using the ratio

 

SOLVING SIMPLE PERCENT PROBLEMS

IS %

OF 100

IS OF

100

Example 6 – What is 30% of 50.

3050x

100 30(50)

100 1500

100 1500

100 100 15

x

x

x

x

YOUR TURN:

1.) 10 is what percent of 18? 2.) 5 is 20% of what number?

100

100

1018

x

18 10(100)

18 1000

18 1000

18 18 55.56%

x

x

x

x

5 20x

20 5(100)

20 500

20 500

20 20 25

x

x

x

x

3.) Find 75% of 25. 4.) 9 is 45% of what number?

100

100

75

25

x

100 75(25)

100 1875

100 1875

100 100 18.75

x

x

x

x

9 45x

45 9(100)

45 900

45 900

45 45 20

x

x

x

x

Homework: p. 174 #7-45 odd