Question

A survey was conducted by a group of students as part of their environment awareness program, in which they collected the following data regarding the number of plants in $20$ houses in a locality. Find the mean number of plants per house.

Number of Plants	0-2	2-4	4-6	6-8	8-10	10-12	12-14
Number of houses	1	2	1	5	6	2	3

Answer 1

$Numberofplants$	$Class-mark$ $x_i$	$Numberofhouses$ $f_i$	$f_i{x}_i$
$0-2$	$1$	$1$	$1$
$2-4$	$3$	$2$	$6$
$4-6$	$5$	$1$	$5$
$6-8$	$7$	$5$	$35$
$8-10$	$9$	$6$	$54$
$10-12$	$11$	$2$	$22$
$12-14$	$13$	$3$	$39$
		$\sum f_i=20$	$\sum f_i{x}_i=162$

$\Rightarrow$ $\overline{x}=\frac{\sum f_i{x}_i}{\sum f_i}=\frac{162}{20}=8.1$

Hence, this is the answer.