Multiple choice

The least number of complete years in which a sum of money loaned at 15% compound interest will have more than doubled is

  1. 4

  2. 3

  3. 5

  4. 6

  5. 7
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the compound interest formula A = P(1 + r/100)^n, we want A > 2P, so (1 + 0.15)^n > 2. For n=4, 1.15^4 = 1.749. For n=5, 1.15^5 = 2.011. Thus, 5 years are required.

AI explanation

For a sum to more than double at 15% compound interest, the amount must be greater than twice the principal, meaning (1.15)^n > 2. Checking the options, (1.15)^4 equals 1.749 and (1.15)^5 equals 2.011. Since the amount first exceeds twice the principal at 5, the required time is 5 years.

Keep practicing — related questions