If mean weight of 60 students is 40. In it mean weight of boys is 50 and of girls is 30. Find the number of boys and girls.

Question

It is a question based on central tendency.

Answer 1

Nidhi,

 

x = the number of girls

y = the number of boys

x + y = 60 ------------------------- equation (1)

Total weight of the students = 60(number of students)*40(their average weight) = 2400

Total weight of girls = x(the number of girls)*30(average weight of girls) = 30x

Total weight of boys = y(the number of boys)*50(average weight of boys) = 50x

Total weight of all students = Total weight of girls + Total weight of boys = 30x + 50y = 2400 ----- equation (2)

Solve equation 1 for either x or y and substitute the result in equation 1.

y=60-x

=> 30x + 50(60-x) = 2400

<=> 30x - 50x + 3000 = 2400

<=> -20x = -600

x = 30

=> y = 30