The average score of boys in an examination of school is 71 and that of girls is 73. The average score of the school in the examination is 71.8, Find the ratio of the number of boys to number of girls who appeared in examination.

Answer

A) 2:3

B) 3:2

C) 3:4

D) 4:3

Solution:

We assume the proportion of boy is P, the proportion of girl is (1-P)

The equation is

71P + 73(1-P) = 71.8

P = 0.6

So boy to girl is 0.6:0.4 = 3:2

We choose (B)