Question

Find the mean of the following frequency distribution:

Class interval:	0-6	6-12	12-18	18-24	24-30
Frequency:	$7$	$5$	$10$	$12$	$6$

Answer 1

Answer:-

Class interval	Frequency	$x_i$	$f_i{x}_i$
0-6	7	3	21
6-12	5	9	45
12-18	10	15	150
18-24	12	21	252
24-30	6	27	162
	$\Sigma f_i=40$		$\Sigma f_i{x}_i=630$

$mean=\frac{\Sigma f_i{x}_i}{\Sigma f_i}=\frac{630}{40}=15.75$