The ratio of the number of boys and girls in a college is 7 : 8. If the percentage iikcrease 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
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), i . e . ( 120/100 X 7x ) and ( 110/100 X 8x ) i . e . 42x/5 and 44x/5 Required ratio = 42x/5 : 44x/5 = 21 : 22