Question

Kunal has a recurring deposit account in a post office for 3 years at an interest of 8.5% per annum. If he gets Rs. 5661 as interest at the time of maturity then the monthly instalment is

• A. 1000
• B. 1400
• C. 1200
• D. 800

Answer 1

The correct option is C

1200

Let the principle be P
n = 3 $\times$ 12 = 36 months
r= 8.5% p.a
I = 5661
Interest is given by
I = $\frac{P\times n(n+1)}{2\times 12}\times \frac{r}{100}$
5661 = $\frac{P\times 36\times 37}{2\times 12}\times \frac{8.5}{100}$
P = Rs.1200