Question

The average weights of the students of a class is 60 kg. If eight new students of average weight 64 kg join the class, the average weight of the entire class becomes 62 kg. How many students were there in the class initially?

Answer 1

Let initial no. Of students=x
Avg. Wt. = 60kg
Therefore, total wt. = 60x

Again,
No. Of students= 8
Avg. Wt. = 64kg
Therefore, total wt.= 64*8=512kg

Now, total avg. Wt.=62kg
Total students= x+8
Therefore, total wt. =62*(x+8) = 62x + 496

A/Q
60x + 512= 62x+496
-› 512-496 = 62x - 60x
-›2x=16
-› x =16/2 = 8

Therefore, initial no. Of students=x=8