Aptitude Day 185

Problems on Simple Interest:

1. A borrowed some money at 3% p.a. for the 1^st year, at the rate of 6% p.a. for the next 3 years, and at the rate of 9% p.a. for the period beyond 6 years. If he pays a total interest of 22800 at the end of 8 years, how much money did he borrow?

Solution:

                   Let the borrowed money or principal be x.

                   S.I = PTR/100

                   22800 = (x*1*3)/100 + (x*3*6)/100 + (x*4*9)/100

                   22800*100 = 3x + 18x + 36x

                   2280000 = 57x

                   x = 40000.

2. At what rate percent per annum will a sum of money double in 10 years?

Solution:

                   Here S.I = P since the amount will be doubled in 10 years.

                   S.I = PTR/100

                   R = P*100/PT

                   R = 100/10

                   R = 10 %