Question

If a sum of money placed at compound interest doubles itself in 5 years, then the same amount of money will be 8 times of itself in

• A. 25 years
• B. 20 years
• C. 15 years
• D. 10 years

Answer 1

Answer: (C)

15 years

Let the sum be Rs. $x$.

Then $x$ becomes $2x$ in 5 years,

$2x$ becomes $4x$ in next 5 years,

$4x$ becomes $8x$ in next 5 years.
Hence, $x$ becomes $8x$ in 15 years.