There are 75 boys and 45 girls in the class. If the average weight of boys is 60 kg and the average weight of girls is 40 kg, then find the average weight of the whole class.
Show answer & explanation
Correct answer: B
Explanation
The Correct answer is Option 2 i.e. 52.5 kg.
We know that,
Average = Sum of observations/Number of observations
The average weight of the 75 boys = 60kg
So, the sum of the weight of the boys = 75 × 60 = 4500 kg
The average weight of the 45 girls = 40kg
So, the sum of the weight of the girls = 45 × 40 = 1800 kg
Average of the class = (4500 + 1800)/(75 + 45)
⇒ 6300/120 = 52.5 kg