Aptitude Day 88

Ratio and Proportion:

1. In a mixture of 20 litres, the ratio of oil and water is 3:1. If the ratio is to be 1:3, then the quality of water to be further added is :

Solution:

                The sum of the ratio(3+1) = 4.

                (20/4)*3 = 15 litres of oil.

                20-15 = 5 litres of water.

                  

                15/(5+x) = 1/3

                45 = 5+x

                x = 40.    

2. The third proportional to (x²-y²) and (x+y) is:

Solution:

                 Let the third proportional be z.

                 (x²-y²): (x+y) :: (x+y) : z

                 z(x²-y²) = (x+y)²

                 z = (x+y)²/ (x+y)(x-y)

                 z = x+y/x-y.