a
$\mathrm{x}_{\mathrm{i}}$ $\ \ 3 \ \ 4\ \ 5 \ \ 8 \ \ 10 \ \ 11$
$\mathrm{f}_{\mathrm{i}}$ $\ \ 5 \ \ 4 \ \ 4 \ \ 2 \ \ 2 \ \ 3$
($P$) Mean
($Q$) Median
($R$) Mean deviation about mean
($S$) Mean deviation about median
| $\mathrm{x}_{\mathrm{i}}$ |
$\mathrm{f}_{\mathrm{i}}$ |
$\mathrm{x}_{\mathrm{i}}$ $\mathrm{f}_{\mathrm{i}}$ |
$C.F$ |
$\mid \mathrm{x}_{\mathrm{i}}-$ Mean $\mid$ |
$\mathrm{f}_{\mathrm{i}} \mid \mathrm{x}_{\mathrm{i}}-$ Mean $\mid$ |
$\mid \mathrm{x}_{\mathrm{i}}-$ Median $\mid$ |
$\mathrm{f}_{\mathrm{i}} \mathrm{x}_{\mathrm{i}}$ - Median $\mid$ |
| $3$ |
$5$ |
$15$ |
$5$ |
$3$ |
$15$ |
$2$ |
$10$ |
| $4$ |
$4$ |
$16$ |
$9$ |
$2$ |
$8$ |
$1$ |
$4$ |
| $5$ |
$4$ |
$20$ |
$13$ |
$1$ |
$4$ |
$0$ |
$0$ |
| $8$ |
$2$ |
$16$ |
$15$ |
$2$ |
$4$ |
$3$ |
$6$ |
| $10$ |
$2$ |
$20$ |
$17$ |
$4$ |
$8$ |
$5$ |
$10$ |
| $11$ |
$3$ |
$33$ |
$20$ |
$5$ |
$15$ |
$6$ |
$18$ |
| |
$\overline{\Sigma f_1}=20$ |
$\Sigma \mathrm{x}_{\mathrm{i}} \mathrm{f}_{\mathrm{i}}=120$ |
|
|
$\overline{\Sigma f_i} \mid x_i-$ Mean $\mid=54$ |
|
$\Sigma f_i \mid x_i-$ Median $\mid=48$ |
($P$) Mean $=\frac{\Sigma x_i f_i}{\Sigma f_i}=\frac{120}{20}=6$
($Q$) Median $=\left(\frac{20}{2}\right)^{\text {th }}$ observation $=10^{\text {th }}$ observation $=5$
($R$) Mean deviation about mean $=\frac{\Sigma \mathrm{f}_{\mathrm{i}} \mid \mathrm{x}_{\mathrm{i}}-\text { Mean } \mid}{\Sigma \mathrm{f}_{\mathrm{i}}}=\frac{54}{20}=2.70$
($S$) mean deviation about median $=\frac{\Sigma \mathrm{f}_{\mathrm{i}} \mid \mathrm{x}_{\mathrm{i}}-\text { Median } \mid}{\Sigma \mathrm{f}_{\mathrm{i}}}=\frac{48}{20}=2.40$