Explanation:

Sure, let's break down the solution:

- Step 1: Calculate Simple Interest (SI)

- Principle (P) = Rs. 20,500

- Rate (R) = 20% per annum

- Time (T) = 4 years

- Formula: SI = (P × R × T) / 100

- SI = (20,500 × 20 × 4) / 100 = Rs. 16,400

- Step 2: Calculate Total Amount after 4 years (Simple Interest)

- Total Amount = Principal + Simple Interest

- Total Amount = 20,500 + 16,400 = Rs. 36,900

- Step 3: Calculate Compound Interest (CI) on the Amount obtained after Simple Interest

- Principal for CI = Rs. 36,900

- Rate = 10% per annum

- Time = 2 years

- Formula for CI: CI = P × [(1 + R/100)^T - 1]

- CI = 36,900 × [(1 + 10/100)^2 - 1]

- CI = 36,900 × [(1.1)^2 - 1]

- CI = 36,900 × [1.21 - 1]

- CI = 36,900 × 0.21

- CI = Rs. 7,749

- Final Answer: The compound interest obtained is Rs. 7,749.

- Correct Option: Option 4 - 7749