Single correct option
The population of a town increases by 10% in the first year and decreases by 10% in the second year. What is the net percentage change in population over the two years?
- A. No change
- B. 1% increase
- C. 1% decrease
- D. 2% decrease
Show answer and solution
Answer: (C) 1% decrease
Net multiplying factor = 1.10 × 0.90 = 0.99, i.e., the population becomes 99% of the original — a net decrease of 1%. This is a common trap: successive equal percentage increase and decrease do NOT cancel out; the net effect is always a decrease equal to (x²/100)% where x is the common percentage — here (10²)/100 = 1%.
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