A Man deposited certain amount in the Bank at the end of each year. How much amount did he deposited at the end of each year at the rate of 15% simple Interest, so that he will get Rs. 1960 at the end of 4^th year?

Solution

Let the amount be 100 units Interest = 15% 4th year -------------- 100 unit -------------45 (Interest of 3 years) [Interest is at the end] 3rd Year -------------- 100 unit ----------- 30 2nd Year --------------100 unit ------------ 15 1st Year ---------------100 unit ------------- 0 Total Interest = 45 + 30 + 15 + 0 = 90 Total Amount = 400 + 90 = 490 units 490 units = 1960 1 unit = 400 Formula Method :- Formula for Annual Payment/ Annual Income / Annual Installment = (Due Debt ×100)/(100 ×t+ (r × t ×(t-1) )/2)                   = (1960 ×100)/(100 ×4+ (15 × 4 ×(4-1) )/2) = 196000/(400+90)  = 400