Question 101292
"The yearly changes in the population of a city for three consecutive years are, respectively, 20% increase, 30% increase, and 20% decrease.What is the total percent change from the beginning to the end of the third year?" 
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Let the population start at "x".
After a 20% increase the population is 1.20x
After a 30% increase the population is (1.30)[1.20x]
After a 20% decrease the population is (0.80)(1.30)[1.20x = 1.248x
That would be a gain of 24.8% 
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Cheers,
Stan H."The yearly changes in the population of a city for three consecutive years are, respectively, 20% increase, 30% increase, and 20% decrease.What is the total percent change from the beginning to the end of the third year?"