Question

The mean weight of $120$ students of a school is $52.75kg$. If the mean weight of $50$ of them is $51kg$, find the mean weight of the remaining students.

Answer 1

$\Rightarrow$ The mean weight of $120$ students $=52.75kg$

$\therefore$ Sum of the weight of a$120$ students $=(120\times 52.75)kg=6330kg$

$\Rightarrow$ The mean weight of $50$ students $=51kg$

$\therefore$ Sum of the weight of $50$ students $=(51\times 50)kg=2550kg$

$\Rightarrow$ Remaining students $=120-50=70students$

$\Rightarrow$ Weight of $70$ students $=(6330-2550)kg=3780kg$

$\therefore$ The mean weight of $70$ students $=\frac{3780}{70}=54kg$