A sum of money doubles itself at compound interest in 15 years. In how many years will it become four times?
Show answer & explanation
Correct answer: B
Explanation
The sum doubles in 15 years.
Under compound interest:
If it takes T years to become 2 times the original amount ⇒ it will take 2T years to become 4 times the original amount.
T = 15 years
Time required to become 4 times = 2 × 15 = 30 years.