3. Calculate Mean deviation, Coefficient of M.D. from the following grouped data

Class	Frequency
2 - 4	3
4 - 6	4
6 - 8	2
8 - 10	1

Solution:
Mean deviation :
Mean `bar x=(sum f x)/(sum f)`

`=52/10`

`=5.2`

Class `(1)`	`f` `(2)`	Mid value (`x`) `(3)`	`f*x` `(4)=(2)xx(3)`	`|x-bar x|=|x-5.2|` `(5)`	`f*|x-bar x|` `(6)=(2)xx(5)`
2 - 4	3	3	9	2.2	6.6
4 - 6	4	5	20	0.2	0.8
6 - 8	2	7	14	1.8	3.6
8 - 10	1	9	9	3.8	3.8
---	---	---	---	---	---
--	`n=10`	--	`sum f*x=52`	--	`sum f*|x-bar x|=14.8`

Mean deviation of Mean
`delta bar x = (sum f*|x - bar x|)/n`

`delta bar x = 14.8/10`

`delta bar x = 1.48`


Coefficient of Mean deviation `=(delta bar x)/(bar x)`

`=1.48/5.2`

`=0.2846`

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