Quantitative Aptitude • Simple & Compound InterestHard
A sum of money doubles itself in 8 years at compound interest. In how many years will it become 16 times itself?
A. 128 years
B. 64 years
C. 32 years✓ Correct Answer
D. 40 years
💡 Solution & Explanation
With compound interest the sum keeps doubling every 8 years: 2 times after 8 years, 4 times after 16, 8 times after 24, and so on. 16 = 2^4, so it takes 4 doublings: 4 × 8 = 32 years. Multiplying 8 by 16 (128 years) would be the simple-interest way of thinking, which does not apply here.
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