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

Let the total number of boys be 'x' and the total number of girls be 'y'

The average score of boys in the examination is 71

Total score of boys = 71 × x = 71 x

The average score of girls in the examination is 73

Total score of girls = 73 × y = 73 y

So Total marks of the students = 71x + 73y……(1)

The average score of total students = 71.8

So total mark of boys and girls = 71.8 × (x + y)….(2)

So equation (1) and (2) are the same number

So, 71 x + 73 y = 71.8 (x + y)

71.8 x – 71 x = 73 y – 71.8 y

0.8 x = 1.2 y