In a class, there are 60 students. The average weight of the entire class is 42 kg. If there are 36 boys in the class and the average weight of all the boys is 50 kg, then what is the average weight (in kg) of all the girls?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 30.
Total students = 60
The average weight of 60 students = 42 kg
Total weight of 60 students = 60 × 42 = 2520 kg
Total boys in a class = 36
The average weight of boys = 50 kg
Total weight of all boys = 36 × 50 = 1800
Number of girls in the class = 60 - 36 = 24
Total weight of all girls in the class = 2520 - 1800 = 720
Average weight of all girls = 720/24 = 30 kg