Katrina opened a recurring deposit account with a Nationalised Bank for a period of 2 years. If the bank pays interest at the rate of 6% per annum and the monthly instalment is Rs 1,000, find the :
(i) interest earned in 2 years.

Answer

To find the interest earned by Katrina on her recurring deposit account over a period of 2 years, we can use the formula for calculating interest on a recurring deposit.

### Step-by-Step Solution:

1. **Identify the Variables:**
- Monthly installment (P) = Rs 1,000
- Rate of interest (r) = 6% per annum
- Time (n) = 2 years = 24 months

2. **Use the Formula for Interest on Recurring Deposit:**
The formula to calculate the interest earned on a recurring deposit is given by:
\[ I = \frac{P \times n \times (n + 1) \times r}{2400} \]
where:
- \( I \) = Interest earned
- \( P \) = Monthly installment
- \( n \) = Total number of months
- \( r \) = Rate of interest per annum

3. **Substituting the Values:**
Substitute the known values into the formula:
\[ I = \frac{1000 \times 24 \times (24 + 1) \times 6}{2400} \]
Simplifying this:
\[ I = \frac{1000 \times 24 \times 25 \times 6}{2400} \]

4. **Calculating the Numerator:**
Calculate the numerator:
\[ 1000 \times 24 = 24000 \]
\[ 24000 \times 25 = 600000 \]
\[ 600000 \times 6 = 3600000 \]

5. **Calculating the Final Interest:**
Now divide by 2400:
\[ I = \frac{3600000}{2400} = 1500 \]

6. **Conclusion:**
The interest earned in 2 years is Rs 1500.