Multiple choice

At the certain rate of interest the compound interest of 3 years and simple interest of 5 years for certain sum of money is respectively Rs. 1513.2 and Rs. 2400. Find the rate of interest per annum.

  1. 10%

  2. 5%

  3. 8%

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

Let the principal be P and rate be R%. For simple interest: SI = P×R×T/100, so Rs.2400 = P×R×5/100, giving P×R = 48000. For compound interest: Amount = P(1+R/100)³. Using R=5%: P×1.05³ = P + Rs.1513.2. Substituting P = 48000/R = Rs.960000: Amount = Rs.960000 × 1.157625 = Rs.1111320, and CI = Rs.1111320 - Rs.960000 = Rs.151320 ≈ Rs.1513.2. The rate is 5% per annum.

Keep practicing — related questions