Question

Find the mean of the following frequency distribution using steps deviation method.

C.I	0-100	100-200	200-300	30-400	400-500	500-600	600-700
F	10	15	25	25	10	10	5

Answer 1

Class Interval	Frequency $f_i$	Mid values $x_i$	$d_i=x_i-A$	$u_i=\frac{d_i}{h}$	$f_i{u}_i$
0-100	10	50	-300	-3	-30
100-200	15	150	-200	-2	-30
200-300	25	250	-100	-1	-25
300-400	25	350	0	0	0
400-500	10	450	100	1	10
500-600	10	550	200	2	20
600-700	5	650	300	3	15

$A=350,h=100,N=\sum f_i=100$

$f_i{u}_i=40$

$Mean\left(\overline{x}\right)=A+h[\frac{1}{N}\sum f_i{u}_i]$

Put the values

$Mean=390$