Explanation

(b)
On arranging the terms in increasing order of magnitude
40,42,45,47,50,51,54,55,57
Number of terms ,N=9
$\therefore Median = \left( \frac{9 + 1}{2} \right)th\ term = 5th\ term = 50kg$
[table] Weight (kg) | Deviation from median (d) | |d| ; 40 | -10 | 10 ; 42 | -8 | 8 ; 45 | -5 | 5 ; 47 | -3 | 3 ; 50 | 0 | 0 ; 51 | 1 | 1 ; 54 | 4 | 4 ; 55 | 5 | 5 ; 57 | 7 | 7 ; | | |d|=43 [/table]
MD from median=$\frac{43}{9} = 4.78$kg
$\therefore$Coefficient of MD from median
$= \frac{MD}{median}$
$= \frac{4.78}{50} = 0.0956$