Question

the mean weight of 60 students in a class is 40kgs. the mean weight of boys is 50kgs while that of girls is 30kgs. find the number of boys and girls in the class.

Answer 1

total weight60*40is 2400kg
boys50 x+30y=2400__1
x+y=60

multiply by 50 comes
50x+50y=3000__2
from eqn 1. - eqn2
20y=600
y=30 girls 30
x=60-30
boys 30