Exams › SSC CGL (Prelims) › Maths

A sum of money placed at compound interest doubles itself in 5 years. In how many years will it amount to eight times itself at the same rate of interest?

1. 10 years
2. 15 years
3. 7 years
4. 20 years

Correct answer: 15 years

Solution

If the money doubles in 5 years, then one doubling takes 5 years. To become 8 times, it must double 3 times because \(8=2^3\). Therefore, the required time is \(3\times 5=15\) years.

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