Find the period when simple interest on Rs.4000 at 6% per annum will be Rs.400.

Options

A. 20 months
B. 22 months
C. 14 months
D. 18 months

Answer

To find the period when simple interest on Rs.4000 at 6% per annum will be Rs.400, we can use the formula for Simple Interest (SI):

### Step-by-step Solution:

1. **Identify the given values:**
- Principal (P) = Rs.4000
- Rate (R) = 6% per annum
- Simple Interest (SI) = Rs.400

2. **Use the formula for Simple Interest:**
\[ SI = \frac{P \times R \times T}{100} \]
where:
- SI = Simple Interest
- P = Principal
- R = Rate of interest per annum
- T = Time in years

3. **Substitute the known values into the formula:**
\[ 400 = \frac{4000 \times 6 \times T}{100} \]

4. **Simplify the equation:**
- Multiply both sides by 100 to eliminate the fraction:
\[ 400 \times 100 = 4000 \times 6 \times T \]
\[ 40000 = 24000T \]

5. **Solve for T:**
- Divide both sides by 24000:
\[ T = \frac{40000}{24000} \]
\[ T = \frac{10}{6} \text{ years} \]

6. **Convert years to months:**
- Since 1 year = 12 months, we multiply by 12:
\[ T = \frac{10}{6} \times 12 = 20 \text{ months} \]

### Final Answer:
The period when simple interest on Rs.4000 at 6% per annum will be Rs.400 is **20 months**.