Question

The mean deviation about the mean for the following data :
$5,6,7,8,6,9,13,12,15$ is :

• A. $1.5$
• B. $3.2$
• C. $2.89$
• D. $5$

Answer 1

The correct option is C $2.89$

Given data is $5,6,7,8,6,9,13,12,15$
So $\overline{x}=\frac{(5+6+7+8+6+9+13+12+15)}{9}$
$\Rightarrow \overline{x}=9$
The mean deviation about the mean $=\frac{\sum |x_i-\overline{x}|}{N}$
$\because |x_i-\overline{x}|=4,3,2,1,3,0,4,3,6$ and the total number of observation is $9$.
Hence, the mean deviation is $\frac{26}{9}=2.89$