The average weight of 16 students in a class is 50.25 kg, and that of the remaining 8 students is 45.15 kg. What is the average weight of all the students in the class?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 48.55 kg
The average of the whole class is the total weight of both groups divided by the total number of students.
Total weight of the 16 students \(=16\times50.25=804\) kg
Total weight of the 8 students \(=8\times45.15=361.2\) kg
Total weight of all 24 students \(=804+361.2=1165.2\) kg
\(\displaystyle \text{Average}=\frac{1165.2}{24}=48.55\) kg
The average weight of the class is 48.55 kg. It must lie between 45.15 kg and 50.25 kg, which already rules out 64.56 kg, 56.23 kg and 31.44 kg.