In a class of 60 students, 60% are girls. The average weight of the boys is 60 kg and that of the girls is 50 kg. What is the average weight (in kg) of the whole class?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 54
The class average is the total weight of boys and girls divided by 60.
Girls \(=60\%\) of 60 \(=36\); boys \(=60-36=24\)
Total weight of the boys \(=24\times60=1440\) kg
Total weight of the girls \(=36\times50=1800\) kg
\(\displaystyle \text{Average}=\frac{1440+1800}{60}=\frac{3240}{60}=54\) kg
The average weight of the class is 54 kg. It is nearer 50 than 60 because there are more girls.