Question

Shahrukh opened a Recurring Deposit Account in a
bank and deposited 800 per month for 18 months
If he received 15,084 at the time of maturity,
find the rate of interest per annum. ​

Answer 1

Amount deposited by Shahrukh per month = ₹ 800

We know that

No. of months (n) = 1 ½ = 3/2 × 12 = 18 months

We know that

Total principal for one month = 800 × [x (x + 1)]/ 2

Substituting the value of x

= 800 × (18 × 19)/ 2

By further calculation

= ₹ 136800

Interest = PRT/ 100

Substituting the values

= (136800 × r × 1)/ (100 × 12)

So we get

= 114r

So the amount of maturity = P × x + SI

15084 = 800 × 18 + 114r

By further calculation

114r = 15084 – 14400

114r = 684

r = 684/114 = 6%

Hence, the rate of interest per annum is 6%.