The average weight of 20 boys is 60 kg. Together with 30 girls, the average weight of all boys and girls is 54 kg. What is the average weight of 30 girls in kg?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 50.
Total weight of 20 boys = 20 × 60 = 1200 kg
Total weight of all 50 students = 50 × 54 = 2700 kg
Total weight of 30 girls = 2700 - 1200 = 1500 kg
Average weight of 30 girls = 1500 ÷ 30 = 50 kg