Find the mean deviation about the mean for the following data:

Height in $cm$	Number of boys
$95-105$	$9$
$105-115$	$13$
$115-125$	$26$
$125-135$	$30$
$135-145$	$12$
$145-155$	$10$

The mean deviation about the mean for the observations $ -1, 0, 4 $ is:

Let the mean of $6$ observations $1, 2, 4, 5, x,$ and $y$ be $5$ and their variance be $10$. Then their mean deviation about the mean is equal to $........$.

Find the mean deviation of the numbers $3, 4, 5, 6, 7$.

The mean and variance of $10$ observations are $9$ and $34.2$, respectively. If $8$ of these observations are $2, 3, 5, 10, 11, 13, 15, 21$, then the mean deviation about the median of all the $10$ observations is

The mean deviation from the median for the following data is

$x_i$	$2$	$3$	$5$	$7$	$9$
$f_i$	$8$	$6$	$4$	$2$	$1$