Multiple choice

In how much time, will a sum of money become double of itself at 15% per annum simple interest?

  1. $6\frac{1}{4} years$
  2. $6\frac{1}{2} years$
  3. $6\frac{1}{3} years$
  4. $6\frac{2}{3} years$
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D Correct answer
Explanation

For a sum to double, the simple interest must equal the principal. Using SI = (P*R*T)/100, we get P = (P*15*T)/100. Thus, T = 100/15 = 20/3 = 6 2/3 years.

AI explanation

For a sum to double at simple interest, the interest earned must equal the principal, meaning P = P(15/100)(T). Canceling the principal gives 1 = 0.15(T), which simplifies to T = 1 / 0.15. Solving this yields T = 100 / 15 = 20 / 3, which is 6 and two-thirds years.

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