Question

Calculate the mean of the following frequency distribution.

Class	$90-100$	$100-110$	$110-120$	$120-130$	$130-140$
Frequency	$18$	$78$	$80$	$100$	$72$

Answer 1

$Class$	$Frequency$ $f_i$	$x_i$	$f_i{x}_i$
$90-100$	$18$	$95$	$1710$
$100-110$	$78$	$105$	$8190$
$110-120$	$80$	$115$	$9200$
$120-130$	$100$	$125$	$12500$
$130-140$	$72$	$135$	$9720$
	$\sum f_i=348$		$\sum f_i{x}_i=41320$

$\Rightarrow$ $Mean\left(\overline{x}\right)=\frac{\sum f_i{x}_i}{\sum f_i}=\frac{41320}{348}=118.73$