The average number of boys and girls in a class is 75 and the number of boys and girls in the class is increased by 20% and 40% respectively

Q.

The average number of boys and girls in a class is 75 and the number of boys and girls in the class is increased by 20% and 40% respectively. If the total number of students in the class is increased by 40, then find the number of boys in the class initially?

a) 200

b) 150

c) 100

d) 50

e) None of these

Sol:

The total number students in the class = 75 * 2 =

150

Let the number of boys in the class = x

And the number of girls in the class = 150 – x

x * 20/100 + (150 – x) * 40/100 = 40

x/5 + 60 – 2x/5 = 40

x/5 = 20

x = 100

The number of boys in the class initially = 100