Question

Rohan has a recurring deposit account in State Bank of India of Rs 2000 per month at the rate of 10% per annum. He receives Rs 83100 at the time of maturity. What was the time period for which he held the account?

• A. 36 months
• B. 16 months
• C. 24 months
• D. 30 months

Answer 1

The correct option is A

36 months

Let the number of installments be x

Monthly installment = Rs 2000

Equivalent principal for 1 month = 2000 $\times$ $\frac{x(x+1)}{2}$

Interest = 2000 $\times$ $\frac{x(x+1)}{2}$ $\times$ $\frac{1}{12}$ $\times$ $\frac{10}{100}$

2000x + 2000 $\times$ $\frac{x(x+1)}{2}$ $\times$ $\frac{1}{12}$ $\times$ $\frac{10}{100}$= 83100

$x^2+241x–9972=0$

$(x-36)(x+277)=0$

x = 36 and x = -277 (neglecting -277 as $\times$ cannot be negative as it time period)

Therefore, the time for which he held the account = 36 months or 3 years.