In a class of 65 students there are 39 girls. The average weight of these girls is 60Kg and average weight of the full class is 64kgs. What is the average weight of the boys of the class?

Given:
Total number of students = 65

Number of girls = 39

Number of boys = 65−39=26

Average weight of the full class = 64kg
Total weight of the class = 65×64=4160kg

Average weight of girls = 60kg
Total weight of girls = 39×60=2340kg

Total weight of boys = Total weight of class - Total weight of girls

Total weight of boys=4160−2340=1820kg
Average weight of boys =
Number of boys
Total weight of boys
​


Average weight of boys=
26
1820
​
=70kg