The 40 students of a class average 62 marks. The boys average 60 and the girls 65. How many girls are in the class?

Explanation

1. 01

   Alligate the averages: boys : girls $= (65 - 62) : (62 - 60) = 3 : 2$.

2. 02

   Girls $= \frac{2}{5} \times 40 = 16$.