Solving Percent Problems Using Proportions
Recall that percent means part of 100, so a percent can be written as a ratio
using 100 as the denominator of the fraction. For example, 43% can be
written as 10043. Also, recall that a percent problem has a base, B, a part, P,
and a ratio (percent) R, so a proportion can be set up for each type of percent
problem as:
R%
100 %¼
P
B
EXAMPLE
Find 32% of 48.
SOLUTION
32 %
100 %¼
P
48
32 48 ¼100P
1536 ¼100P
1536
100
¼
100 P
100
15 : 36 ¼P
EXAMPLE
What percent of 60 is 45?
SOLUTION
R
100 %¼
45
60
60R¼ 45 100
60R¼ 4500
60 R
60
¼
4500
60
R¼75, so the rate is 75%.EXAMPLE
22% of what number is 17.6?
CHAPTER 8 Ratio and Proportion 159