A sum of Rs. 12000 deposited at compound interest becomes double after 5 years. How much will it be after 20 years?

Answer

To solve the problem step by step, we will calculate how much the amount will be after 20 years, given that a sum of Rs. 12,000 doubles in 5 years at compound interest.

### Step-by-Step Solution:

1. **Identify the Initial Amount and Time Period**:
- Initial Amount (P) = Rs. 12,000
- Time Period for doubling = 5 years

2. **Determine the Amount after 5 Years**:
- Since the amount doubles in 5 years, the amount after 5 years (A) will be:
\[ A = 2 \times P = 2 \times 12,000 = 24,000 \]

3. **Calculate the Amount after 10 Years**:
- The amount after the next 5 years (10 years total) will be double of the amount after 5 years:
\[ A_{10} = 2 \times A_{5} = 2 \times 24,000 = 48,000 \]

4. **Calculate the Amount after 15 Years**:
- The amount after the next 5 years (15 years total) will be double of the amount after 10 years:
\[ A_{15} = 2 \times A_{10} = 2 \times 48,000 = 96,000 \]

5. **Calculate the Amount after 20 Years**:
- The amount after the next 5 years (20 years total) will be double of the amount after 15 years:
\[ A_{20} = 2 \times A_{15} = 2 \times 96,000 = 192,000 \]

6. **Final Answer**:
- Therefore, the amount after 20 years will be Rs. 192,000.

### Summary:
After 20 years, the amount will be Rs. 192,000.

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