Question
Find the mean deviation taking deviation from the mean for the given individual observation
10, 20, 30, 40, 50, 60, 70

Answer

Calculation of Mean Deviation from Arithmetic Mean
S. No. X $|\text{D}|=|\text{X}-\bar{\text{X}}|\bar{\text{X}}=40$
1 10 30
2 20 20
3 30 10
4 40 0
5 50 10
6 60 20
7 70 30
n = 7 $\sum\text{X}=280$ $\sum|\text{D}|=120$
$\bar{\text{X}}=\frac{\sum\text{X}}{\text{n}}=\frac{280}{7}=40$
$\text{MD}_{\bar{\text{X}}}=\frac{\sum|\text{D}|}{\text{n}}=\frac{120}{7}=17.1$
Where, MD = Mean Deviation, $\bar{\text{X}}$ = Arithmetic mean.$\sum|\text{D}|=$ Sum of absolute deviations from actual mean.

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