Question

The mean weight of 60 students of a class is 40kg. The mean weight of boys is 50kg, while that of the girls is 30kg. Find the no. of boys n girls in the school.

Answer 1

Boys=30

Girls=30

Explanation:

Given,

Total number of students=60

Mean weight of 60 students=40kg

Total weight of 60 students=60*40kg=2400kg

Let the number of boys be x and that of the girls is (60-x)

Mean weight of boys=50kg

Total weight of boys=50*x kg

Mean weight of girls=30kg

Total weight of girls=30*(60-x) kg

Then, equating total weights,we get,

50x+30(60-x)=2400

or,50x+1800-30x=2400

or,20x=600

or,x=30

Thus, Number of boys,x=30

and, Number of girls,(60-x)=60-30=30