question_answer

In a class, the mean weight of 60 students is 40 kg. The mean weight of boys is 50 kg while that of the girls is 30 kg. The number of boys and girls respectively are ____.

A)  30, 30                         

B)  35, 25 

C)         25, 35             

D)         20, 40             

Correct Answer: A

Solution :

Mean weight of 60 students = 40 kg Let the number of boys be Then, the number of girls Now, mean weight of boys = 50 Sum of weights of boys               ?(i) Also, mean weight of girls = 30 Sum of weights of girls       ?(ii) Now, Number of boys = 30 And number of girls