Explanation

(b)
Arranging the terms in increasing order
[table] Value $\mathbf{x}$ | Frequency $\mathbf{f}$ | Commulative frequency ; 7 | 2 | 2 ; 8 | 1 | 3 ; 9 | 5 | 8 ; 10 | 4 | 12 ; 11 | 6 | 18 ; 12 | 1 | 19 ; 13 | 3 | 22 [/table]
$\because$ $N = 22$
$\because$ Median number $= \frac{N + 1}{2} = 11.5$
Which comes under the cumulative frequency the corresponding value of $x$will be the median ie,
Median=10