Question

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

• A. 12
• B. 10
• C. 8
• D. 14

Answer 1

Answer: (C)

Let there be $n$ students in the class. The total weight of the students after the eight new students join the class.
$60n+64(8)=62(n+8)$
$\Rightarrow 60n+64(8)=62n+62(8)$
$\Rightarrow 62n-60n=64(8)-62(8)$
$\Rightarrow 2n=8(2)\Rightarrow n=8$
$\therefore$ Initially, there were 8 students in the class.