Chapter 10: Lesson 4: Solving Percent Problems with Proportions Objective: Learn to use proportions to solve percent problems.
Another way to solve percent problems is by using proportions. Steps: First re-write percents as fractions by writing them over a 100. Then use the information in the problem to write the other ratio. Multiply to find the cross products. Use the inverse operation. Solve for the variable. P = is 100 of
Example 1: What number is 47% of 280? 100 of 47 = N 100 280 p = is 100 of 47 = N 100 280 100N = 47 × 280 100N = 13,160 100 100 N = 131.60
Example 2: P = is 38 = 52 52 is 38% of what number? 100 of 100 N 38 = 52 100 N 38 N = 5200 38 38 N = 136.84
Example 3: 45 is what percent of 90? P = 45 100 90 100 90 100 90 100 90 90P = 45 x 100 90P = 4500 90 90 P = 50%
Homework: Use proportions to solve percent exercises. What number is 70% of 45? 15 is 25% of what number? What number is 75% of 125? 7 is what percent of 77? What number is 23% of 75?