Question

Find the mean deviation about mean for the following data:

Score $\left(x\right)$	$6$	$20$	$8$	$18$	$16$	$12$	$14$	$10$
Frequency $\left(f\right)$	$2$	$7$	$11$	$27$	$18$	$13$	$17$	$5$

Answer 1

Score	Frequency $f_i$	$|x_i-\overline{x}|$	$f_i|x_i-\overline{x}|$
6 20 8 18 16 12 4 10	2 7 11 27 18 13 17 5	10.5 5.5 1.5 14.5 5.5 0.5 4.5 7.5	21 38.5 16.5 391.5 99 6.5 76.5 37.5
	$100$	$50$	$687$

$\overline{x}=\frac{100}{8}=12.5$

Therefore, Mean devation $=\frac{\sum f(x-\overline{x})}{\sum f_i}=\frac{687}{100}=\mathrm{6.87.}$