Percent Problems: Proportion Method
To solve percent problems using proportions
Problems that can be solved using the basic percent equation can also be solved
using proportions.
The proportion method is based on writing two ratios. One ratio is the percent ratio,
written as 100
percent . The second ratio is the amount-to-base ratio, written as base
amount .
These two ratios form the proportion:
base
amountpercent =
100
To use the proportion method, first identify the percent, the amount, and the Base (the
base usually follows the phrase “percent of”).
Example 1: What is 23 % of 45?
45100
23 n
=
23(45) = 100n
1035 = 100n
100
100
100
1035 n
=
10.35 = n
Example 2: What percent of 25 is 4?
25
4
100
=
n
25n = 100(4)
25n = 400
%16
25
400
25
25 === n
n
Math 0300
Student Learning Assistance Center - San Antonio College
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