Find the mean deviation about the mean for the following data: $12, 3, 18, 17, 4, 9, 17, 19, 20, 15, 8, 17, 2, 3, 16, 11, 3, 1, 0, 5$.

Find the mean deviation about the median of the following distribution:
$ \begin{array}{|l|l|l|l|l|l|} \hline \text{Marks obtained} & 10 & 11 & 12 & 14 & 15 \\ \hline \text{Number of students} & 2 & 3 & 8 & 3 & 4 \\ \hline \end{array} $

If the mean deviation of $5$ observations about the mean $3$ is $1.2$,find the coefficient of mean deviation.

The mean deviation from the mean for the data $ 3, 10, 10, 4, 7, 10, 5 $ is:

The following data represents the frequency distribution of $20$ observations.

$x_i$	$3$	$4$	$5$	$8$	$10$	$11$
$f_i$	$\alpha+2$	$(\alpha-1)^2$	$4$	$\alpha-1$	$2$	$\alpha$

Then its mean deviation about the mean is

If $m$ and $M$ denote the mean deviations about the mean and about the median respectively of the data $20, 5, 15, 2, 7, 3, 11$,then the mean deviation about the mean of $m$ and $M$ is