David opened a Recurring Deposit Account in a bank and deposited ₹ 300 per month for two years. If he received ₹ 7725 at the time of maturity, find rate of interest per annum.

Amit deposited ₹ 150 per month in a bank for 8 months under Recurring Deposit Scheme. What will be the maturity value of his deposits, if the rate of interest is 8% per annum and interest is calculated at end of every month ?

Mr. Gulati has a Recurring deposit account of ₹ 300 per month. If the rate of interest is 12% and the maturity value of this account is ₹ 8100; find the time (in years) of this recurring deposit account.

Mr. Gupta opened a recurring deposit account in a bank. He deposited ₹ 2500 per month for two years. At the time of maturity he got ₹ 67500. Find :

(i) the total interest earned by Mr. Gupta

(ii) the rate of interest per annum.