Priyanka has a recurring deposit account of ₹1000 per month at 10% per annum.

Priyanka has a recurring deposit account of ₹1000 per month at 10% per annum. If she gets ₹5550 as interest at the time of maturity, find the total time for which the account was held.

Answer

Monthly Deposit = ₹1000, rate of interest 10%
Total interest = ₹5550
Let n be the number of months
∴ 5550 = 1000 × n(n + 1) × 10 / 100 × 2 × 12                                                                                                                         555 555 × 24 / 10 = n² + n or n² + n - 1332 = 0
(n + 37)(n - 36) = 0
∴ n = 36 months
i.e. n = 3 years