The population of a town increases 4 % annually but is decreased by emigration annually to the extent of (1/2) %. What will be the increase percent in three years?
Correct answer: D. 10.8
- A. 9.8
- B. 10
- C. 10.5
- D. 10.8
Explanation
Each year the population is multiplied by 1.04 and then by 0.995, giving a yearly factor of 1.035. Over three years, the increase is (1.035^3 - 1) x 100 = 10.87%, approximately 10.8%. The common mistake is option c, 10.5%, which simply adds 3.5% for each year and ignores annual compounding.
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About Percentages
Percentages express a quantity as parts per hundred and support calculations involving increases, decreases, discounts, commissions, taxes, and successive changes. Questions require distinguishing percentage change from percentage points and identifying the original value when a final value and its percentage change are given.
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