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

$x_i$	$5$	$10$	$15$	$20$	$25$
$f_i$	$7$	$4$	$6$	$3$	$5$

First,calculate the mean $\bar{x}$:

$x_i$	$f_i$	$f_i x_i$
$5$	$7$	$35$
$10$	$4$	$40$
$15$	$6$	$90$
$20$	$3$	$60$
$25$	$5$	$125$
Total	$N = 25$	$\sum f_i x_i = 350$

$\bar{x} = \frac{\sum f_i x_i}{N} = \frac{350}{25} = 14$
Now,calculate the mean deviation about the mean:

$x_i$	$f_i$	$|x_i - \bar{x}|$	$f_i |x_i - \bar{x}|$
$5$	$7$	$|5-14| = 9$	$63$
$10$	$4$	$|10-14| = 4$	$16$
$15$	$6$	$|15-14| = 1$	$6$
$20$	$3$	$|20-14| = 6$	$18$
$25$	$5$	$|25-14| = 11$	$55$
Total	$25$	-	$158$

$M.D.(\bar{x}) = \frac{\sum f_i |x_i - \bar{x}|}{N} = \frac{158}{25} = 6.32$