16Hit1600
Problem-Solving and Data AnalysisHardCombining two percent increases

Problem-Solving and Data Analysis practice question

A town's population increased by 10% in one year and then by 20% in the following year. By what percent did the population increase over the two years combined?

Answer: 32

Multiply the growth factors: 1.10 × 1.20 = 1.32, an increase of 32%. (Check with 100: 100 → 110 → 132.)

Common wrong answers

If you answered 2
2 is 1.10 × 1.20 with a misplaced decimal, or 20 − 10 − 8. The combined factor is 1.32.
If you answered 30
30 adds the percents. But the 20% is taken of the already-larger population, so the total is more than 30%.
If you answered 132
132 is the final population as a percent of the original. The INCREASE is 132 − 100 = 32%.

More Problem-Solving and Data Analysis questions

Not affiliated with the College Board. SAT is a trademark of the College Board.