Question

Rishabh has the recurring deposit account in a post office for 3 years at 8% p.a. simple interest. If he gets Rs 9,990 as interest at the time of maturity, find:

1) The monthly instalment.

2) The amount of maturity.

Answer 1

Let Installment per month = Rs P

Number of months(n) = 36

Rate of interest(r)= 8% p.a.

`:. S.I = P xx (n(n + 1))/(2 xx 12) xx r/100`

`= P xx (36(36 + 1))/(2 xx 12) xx 8/100`

`= P xx  (36(36 + 1))/(2 xx 12) xx 8/100`

`= P xx 1332/24 xx 8/100 = "Rs"  4.44 P`

Given interest = Rs 9,990

Then 4.44P = Rs 9990

`=> P = "Rs"  9990/4.44 = "Rs"  2250`

2) Maturity value = Rs (2,250 × 36) + Rs 9,990 = Rs 90990