Aptitude Day 200

Problems on Simple Interest:

1. A invested an amount of 1000 at the rate of 9% p.a. simple interest and another amount at the rate of 4% p.a. simple interest. The total interest earned at the end of 1 year on the total amount invested became 8% p.a. Find the total amount invested.

Solution:

                 (1000*9*1)/100 + (x*4*1)/100 = [(1000+x)*8*1]/100

                 9000+4x = 8000+8x

                 x = 250.

                 Principal = 1000+250 = 1250.

2. A finds that due to a fall in the annual rate of interest from 12% to 9(3/2)%, his yearly income diminishes by 90. His capital is:

Solution:

                 Let the principal be x.

                 (x*12*1)/100 – (x*21/2*1)/100 = 90

                 3x/100[4-7/2] = 90

                 x = 90*200/3

                 x = 6000.