Multiple choice

A sum of money invested at compound interest amounts in 3 years to Rs 2400 and in 4 year to Rs 2520. The interest rate per annum is - कोई धन चक्रवृद्धि ब्याज की दर से 3 वर्षो में 2400 रू तथा 4 वर्षो में 2520 रू. हो जाते है। ब्याज की दर वार्षिक है।

  1. 12%

  2. 10%

  3. 15%

  4. 5%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The difference between 4-year and 3-year amounts (Rs. 2520 - Rs. 2400 = Rs. 120) is the interest earned in the 4th year on the 3-year amount. If rate is r%, then 2400 × r/100 = 120, giving r = 5%. Verification: Year 3 amount = 2400, Year 4 = 2400 × 1.05 = 2520 ✓. Starting principal would be: 2400 ÷ (1.05)³ ≈ Rs. 2071.

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