Question

In a class, a student is replaced by a teacher and the average is increased by $\frac{3}{4}$kg. If total students were $60$ and the average weight of the students were $40$ kg, find the weight of the teacher.

Answer 1

$\Rightarrow$ Average weight of $60$ students is $40kg$

$\therefore$ Sum of weight of all $60$ students $=(60\times 40)kg=2400kg$

$\Rightarrow$ When a student is replace by teacher then average weight increased by $\frac{3}{4}kg$

$\therefore$ New average weight $=40+\frac{3}{4}=40.75$

$\Rightarrow$ Now, sum of weight of $60$ students and teacher $=(60\times 40.75)kg=2445kg$

$\therefore$ The weight of teacher $=(2445-2400)kg=45kg$