Question

Shahrukh opened a Recurring Deposit Account in a bank and deposited  Rs 800 per month for 1 1/2 years. If he received Rs 15084 at the time of maturity, Find the rate of interest per annum.

Answer 1

P = Money deposited per month = Rs 800

n = Time for which the money is deposited = 1 ` 1/2 "years" ="18 months"`

Let the rate of interset be r% per annum , then

                                      Now M.V = `P xx  (n(n + 1))/(2 xx 12) xx r/100`

                                                    `= 800 xx (18xx19)/(2xx12)r /100`

                                                    = ₹ 114r

               Total money deposited = 18 × 800 = ₹ 14,400

Since money deposited + interest = Maturity value 

                                14,400 + 144r = 15,084

                                              114r = 15,084 - 14,400

                                               114r = 684

                                                    ` r = 684/114 = 6%`

Thus the rate of interest per annum is 6%