Multiple choice

At what rate of interest per annum will a sum becomes $5$ times in $20$ years at S.I.?

  1. $10 \%$
  2. $16 \%$
  3. $20 \%$
  4. $25 \%$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For simple interest, the amount A = P + SI. If A = 5P, then SI = 4P. Using SI = (P * R * T) / 100, we get 4P = (P * R * 20) / 100. Solving for R gives 4 = R / 5, so R = 20%.

AI explanation

Using the simple interest formula, if a sum becomes 5 times in 20 years, the interest earned is 4 times the principal. Setting up the equation 4P = (P * R * 20) / 100 and canceling P gives 4 = 20R / 100. Solving for R yields R = (4 * 100) / 20, which equals 20%.

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