Basic Mathematics for College Students

524 Chapter 6 Percent

Self Check 5

9 is what percent of 16?

Now TryProblem 31







Self Check 6

What percent of 5 is 8.5?

Now TryProblem 35

 

To make the calculations easier, it is helpful to simplify the ratio at this time.

On the left side, simplify:.

To solve the proportion, find the cross products:.

Then set them equal.

To simplify the left side of the equation, do the

multiplication: 19  100 1,900.

To undo the multiplication by 20 and isolate x

on the right side, divide both sides of the equation

by 20. Then remove the common factor of 20 from

the numerator and denominator.

On the left side, divide 1,900 by 20.

We have found that 38 is 95% of 40. That is, 95% of the wells mentioned in the

newspaper article were declared safe.

95 x

1,900

20



20

1

x

20

1

1,900 20 x

19  100  20 x 2019  100 x

38

40



2

1

 19

2

1

 20



19

20

19

20



x

100

3840

95

20  1,900

 180

100

 100

0

 

EXAMPLE (^5) 14 is what percent of 32?
StrategyWe will identify the percent, the base, and the amount and write a
percent proportion of the form.
WHYThen we can solve the proportion to find the unknown percent.
SolutionFirst, we write the percent proportion.
is of
This is the proportion to solve.
To make the calculations easier, it is helpful to simplify the ratio at this time.
On the left side, simplify:.
To solve the proportion, find the cross products:.
Then set them equal.
To simplify the left side of the equation, do the
multiplication: 7  100 700.
To undo the multiplication by 16 and isolate x
on the right side, divide both sides of the equation
by 16. Then remove the common factor of 16 from
the numerator and denominator.
On the left side, divide 700 by 16.
Thus, 14 is 43.75% of 32.
43.75x

700

16



16

1

x

16

1

700  16 x

7

16 

x

7  100  16 x 100

14

32



2

1

 7

2

1

 16



7

16

7

16



x

100

1432

14

32



x

100

amount percent base

14 what percent 32?

amountbase percent 100

43.75

(^16)  700.00
 64
60
 48
12 0
 11 2
80
 80
0
EXAMPLE (^6) What percent of 6 is 7.5?
StrategyWe will identify the percent, the base, and the amount and write a
percent proportion of the form.
WHYThen we can solve the proportion to find the unknown percent.
amountbase percent 100