An amount of Rs.4800 is invested with compound interest applied for three consecutive years. The interest rates are 10% for the first year, 20% for the second year, and 25% for the third year. What is the total interest earned after three years?

Explanation

Let the final amount after three years be A. Using compound interest with varying rates: A = 4800 × (1 + 0.10) × (1 + 0.20) × (1 + 0.25) = 4800 × 1.10 × 1.20 × 1.25 = Rs.7920. The interest earned is the difference between the final amount and the principal: 7920 - 4800 = Rs.3120.