Multiple choice

A sum of money at compound interest becomes double of itself in 15 yrs. The rate of interest is

  1. 5.1%

  2. 5%

  3. 4.7%

  4. 4.8%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the compound interest formula A = P(1 + r/100)^n, 2P = P(1 + r/100)^15. 2 = (1 + r/100)^15. Solving for r gives approximately 4.73 percent.

AI explanation

Using the compound interest formula, we have 2P = P(1 + r)^15, which means (1 + r)^15 = 2. Solving for the rate requires taking the 15th root of 2, so r = 2^(1/15) - 1. Calculating this gives an exact rate of 4.73%, which corresponds to the closest provided choice. The result is 4.7%.

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