Question

If the mean of a data is $20.2$. Find the value of m.

Observation	$10$	$15$	$20$	$25$	$30$
Frequency	$6$	$8$	m	$10$	$6$

Answer 1

$Observation$ $x_i$	$Frequency$ $f_i$	$f_i{x}_i$
$10$	$6$	$60$
$15$	$8$	$120$
$20$	$m$	$20m$
$25$	$10$	$250$
$30$	$6$	$180$
	$\sum f_i=30+m$	$\sum f_i{x}_i=610+20m$

$\Rightarrow$ $Mean\left(\overline{x}\right)=\frac{\sum f_i{x}_i}{\sum f_i}$

$\therefore$ $20.2=\frac{610+20m}{30+m}$

$\therefore$ $606+20.2m=610+20m$

$\therefore$ $0.2m=4$

$\therefore$ $m=20$