Ratio and Proportion - General Aptitude

Q1:

The ratio of the number of boys and girls in a college is 7 : 8. If the percentage increase in the number of boys and girls be 20% and 10% respectively, what will be the new ratio?

A 8 : 9

B 17 : 18

C 21 : 22

D Cannot be determined

ANS:C - 21 : 22

Originally, let the number of boys and girls in the college be 7x and 8x respectively. Their increased number is (120% of 7x) and (110% of 8x).

120 x 7x and 110 x 8x
100 100
42x and 44x
5 5
The required ratio = 42x : 44x = 21 : 22.
5 5