If the mean of $4, 7, 2, 8, 6$ and $a$ is $7$,then the mean deviation from the median of these observations is

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

${x_i}$	$2$	$5$	$6$	$8$	$10$	$12$
${f_i}$	$2$	$8$	$10$	$7$	$8$	$5$

The mean deviation about the mean of the set of first $n$ natural numbers,when $n$ is an even number,is equal to:

When a die is rolled $42$ times, it is observed that a face having the digit $i$ occurred $2i$ times. The mean deviation from the mean of this discrete frequency distribution is

The frequency distribution of the age of students in a class of $40$ students is given below.

Age	$15$	$16$	$17$	$18$	$19$	$20$
No. of students	$5$	$8$	$5$	$12$	$X$	$Y$

If the mean deviation about the median is $1.25$,then $4X + 5Y$ is equal to:

Calculate the mean deviation from the median of the following data:

Class interval	$0-6$	$6-12$	$12-18$	$18-24$	$24-30$
Frequency	$4$	$5$	$3$	$6$	$2$