The average weight of a group of 150 students in a class is 60 kg. If the mean of weights of all the 50 boys in the class is 70kg, then the average weight of 100 girls in the class is equal to (A) 65 kg (B) 50 kg (C) 60 kg (D) 55 kg
Answers
Answer:
The average weight of 100 girls = option D = 55 kg
Step-by-step explanation:
Given : Total no of students in a class = 150
Average weight of students = 60 kg
No of boys = 50
Mean weight of boys = 70 kg
No of girls = 100 nos
Average weight of girls = G = ?
Solution : i) Total weight of students = Total weight of boys + total weight of
girls
ii) Total weight of students = no of students x average weight of students
= 150 x 60
= 9000 kg
ii) Total weight of boys = average weight of boys x no of boys
= 70 x 50
= 3500
iv) Total weight of girls = average weight of girls x no of girls
= G x 100
= 100G
Substituting ii), iii) & iv) in i), we get
9000 = 3500 + 100G
100G = 9000-3500
100G = 5500
G = 5500/100
= 55 kg
The average weight of 100 girls = option D = 55 kg