Problem-Solving and Data AnalysisVery hardPopulation after a rise and a fall
Problem-Solving and Data Analysis practice question
A town's population grew by 10 percent in one year and fell by 10 percent the next year. The population at the end of the two years is what percent of the population at the start?
Answer: 99
1.10 × 0.90 = 0.99, so the population is 99 percent of its starting value.
Common wrong answers
- If you answered 90
- 90 applies only the fall.
- If you answered 100
- 100 assumes the two changes cancel exactly.
- If you answered 110
- 110 applies only the rise.
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