Aptitude Day 103

Ratio and Proportion :

1. In a school, 30% of the boys are same in the number as 1/2 of the girls. What’s the ratio of boys and girls in that school?

Solution:

                  (30/100)B = (1/2)G

                  B/G = 100/60 = 5/3

                  The required ratio is 5:3

2. Three containers have their volumes in the ratio 1:2:5. They are full of mixtures of milk and water. The mixtures contain milk and water in the ratio of (1:3), (2:1) and (3:1) respectively. The contents of all these three containers are poured into a fourth container. The ratio of milk and water in the fourth container is:

Solution:

                 Let their volumes be x, 2x and 5x respectively.

                

                Milk in the 3 containers = x(1/4) + 2x(2/3) +5x(3/4)

                                                           = x/4 + 4x/3 + 15x/4

                                                           = 64x /12.

               Water in the 3 containers = x(3/4) +2x(1/3) + 5x(1/4)

                                                             = 3x/4 + 2x/3 + 5x/4

                                                             = 32x/12.

                The required ratio =  64x/12 : 32x/12

                                              =  2:1