Formula

1. Mean deviation of Mean `delta bar x = (sum |x - bar x|)/n`

2. Mean deviation of Median `delta bar x = (sum|x - M|)/n`

3. Mean deviation of Mode `delta bar x = (sum|x - Z|)/n`

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Examples
1. Find Mean deviation about Mode from the following ungrouped data
`85,96,76,108,85,80,100,85,70,95`

Solution:
Mode :
In the given data, the observation `85` occurs maximum number of times (`3`)

`:. Z = 85`

`x`	`|x - Z| = |x - 85|`
85	0
96	11
76	9
108	23
85	0
80	5
100	15
85	0
70	15
95	10
---	---
`880`	`88`

Mean deviation of Mode
`delta bar x = (sum |x - Z|)/n`

`delta bar x = 88/10`

`delta bar x = 8.8`


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

`=8.8/85`

`=0.1035`

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2. Find Mean deviation about Mode from the following ungrouped data
`69,66,67,69,64,63,65,68,72`

Solution:
Mode :
In the given data, the observation `69` occurs maximum number of times (`2`)

`:. Z = 69`

`x`	`|x - Z| = |x - 69|`
69	0
66	3
67	2
69	0
64	5
63	6
65	4
68	1
72	3
---	---
`603`	`24`

Mean deviation of Mode
`delta bar x = (sum |x - Z|)/n`

`delta bar x = 24/9`

`delta bar x = 2.6667`


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

`=2.6667/69`

`=0.0386`

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