Quantitative Aptitude • Simple & Compound InterestHard
A sum of money doubles itself in 11 years at compound interest. In how many years will it become 16 times itself?
A. 44 years✓ Correct Answer
B. 55 years
C. 88 years
D. 176 years
💡 Solution & Explanation
With compound interest the sum keeps doubling every 11 years: 2 times after 11 years, 4 times after 22, 8 times after 33, and so on. 16 = 2^4, so it takes 4 doublings: 4 × 11 = 44 years. Multiplying 11 by 16 (176 years) would be the simple-interest way of thinking, which does not apply here.
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