In what time willRs. 1200 earn an interest of Rs. 240 at 5% per annum ?

Answer

To solve the problem of finding the time it takes for Rs. 1200 to earn an interest of Rs. 240 at a rate of 5% per annum, we can use the formula for Simple Interest (SI):

\[ \text{SI} = \frac{P \times R \times T}{100} \]

Where:
- SI = Simple Interest
- P = Principal amount (initial investment)
- R = Rate of interest per annum
- T = Time in years

### Step-by-step Solution:

1. **Identify the given values:**
- Principal (P) = Rs. 1200
- Simple Interest (SI) = Rs. 240
- Rate of Interest (R) = 5%

2. **Rearrange the formula to find time (T):**
\[ T = \frac{SI \times 100}{P \times R} \]

3. **Substitute the known values into the formula:**
\[ T = \frac{240 \times 100}{1200 \times 5} \]

4. **Calculate the denominator:**
\[ 1200 \times 5 = 6000 \]

5. **Now substitute back into the equation:**
\[ T = \frac{24000}{6000} \]

6. **Perform the division:**
\[ T = 4 \]

7. **Conclusion:**
The time required for Rs. 1200 to earn an interest of Rs. 240 at a rate of 5% per annum is **4 years**.