Question

In a class of 80 students, 60% are girls and the rest are boys. The average weight of boys is 5% more than that of girls. If the average weight of all the students is 51 kg, then what is the average weight (in kg) of the girls?

• A. 52.5
• B. 55
• C. 47.5
• D. 50

Answer 1

Answer:

D. 50

Total number of students = 80 The average weight of all the students = 51 kg 60% are girls and the rest are boys Number of boys = 80 × (40/100) = 32 Number of girls = 80 - 32 = 48 Let the average weight of the girls = A Average weight of the boys = A × 105/100 = 1.05A Sum of weight of students = 80 × 51 = 4080 kg Sum of weights = 48A + 32 × 1.05A = 81.6A 81.6A= 4080 A = 50