Question

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

Answer 1

Calculation of Mean Deviation from Arithmetic Mean

$\begin{array}{ccc}\text{S. No.}& \text{X}& |D|=|x-\overline{X}|\\ & & X=40\\ 1& 10& 30\\ 2& 20& 20\\ 3& 30& 10\\ 4& 40& 0\\ 5& 50& 10\\ 6& 60& 20\\ 7& 70& 30\\ N=7& \sum =280& \sum |D|=120\end{array}$

$\overline{X}=\frac{\sum X}{N}=\frac{280}{7}=40$

$MD=\frac{\sum |D|}{N}=\frac{120}{7}=17.1$

where, MD = Mean deviation, $\overline{X}$ = Arithmetic mean.

$\sum |D|$ = Sum of absolute deviations from actual mean