Find the mean deviation about the mean for the following data :
9,2,7,10,5,12,4,7

Explanation

`because` Mean of the given data is `barx=(9+2+7+10+5+12+4+7)/8=56/8=7`
`therefore` Deviations of the observations from the mean `barx` i.e. x-`barx` are `{:(9-7,2-7,7-7,10-7,5-7,12-7,4-7,7-7),(=2,-5,0,3,-2,5,-3,0):}`
`therefore` Absolute values of the deviation i.e. `|x-barx|` are 2,5,0,3,2,5,3,0
`therefore M.D.(barx)=(Sigma|x_i-barx|)/8=20/8=2.5`