SAT Math Multiple Choice Practice Question 278: Answer and Explanation

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Question: 278

14. The population of Bumpton increased by 10% from 1980 to 1990 and decreased by 10% from 1990 to 2000. What is the net percent change in the population of Bumpton from 1980 to 2000?

A. -9%
B. -1%
C. +0%
D. +1%
E. +9%

Correct Answer: B

Explanation:

B It is easier to pick a simple value for the "starting" population in 1980, like 100. Since the population increased by 10% from 1980 to 1990, the 1990 population must have been . Since it decreased by 10% from 1990 to 2000, the 2000 population must have been . From 1980 to 2000, then, the percent change was .

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