There are 50 students in a class of which 40 are boys and the rest girls. The average weight of the students in the class is 44 kg and average weight of the girls is 40 kg. Find the average weight of boys.

Solution:

Total number of students = 50

No. of boys = 40

No. of girls = 50-40 = 10

Average weight of 50 students = 44 kg

So sum of weight = 44×50 = 2200 kg

Average weight of girls = 40 kg

So sum of weight of girls = 40×10 = 400 kg

Total weight of boys = 2200-400 = 1800 kg

Average weight of boys = 1800/40 = 45 kg

Hence the average weight of boys is 45 kg.