The following table shows the position of three persons between $8.00\, am$ to $8.20\, am$.

Time	Position of Person $A$ $(km)$	Position of Person $B$ $(km)$	Position of Person $C$ $(km)$
$8.00\, am$	$0$	$0$	$0$
$8.05\, am$	$4$	$5$	$10$
$8.10\, am$	$13$	$10$	$19$
$8.15\, am$	$20$	$15$	$24$
$8.20\, am$	$25$	$20$	$27$

$(i)$ Who is moving with constant speed?
$(ii)$ Who has travelled the maximum distance between $8.00\, am$ to $8.05\, am$?
$(iii)$ Calculate the average speed of person $A$ in $km\, h^{-1}$.

(N/A) $(i)$ Person $B$ is moving with constant speed because he travels an equal distance of $5\, km$ in equal intervals of time (every $5\, minutes$).
$(ii)$ Person $C$ has travelled the maximum distance, which is $10\, km$ between $8.00\, am$ and $8.05\, am$.
$(iii)$ Average speed of person $A = \frac{\text{Total distance travelled by } A}{\text{Total time taken}}$
$= \frac{25\, km}{20\, min} = \frac{25\, km}{(20/60)\, h} = \frac{25 \times 60}{20}\, km\, h^{-1} = 75\, km\, h^{-1}$.