A train started from rest at $07$:$00.$ The train accelerated for $5$ minutes to reach a speed of $v$

$k\frac{m}{h}r.$ The train maintained this speed for $45$ minutes then decelerated for $10$ minutes to reach

a speed of $0k\frac{m}{h}r.$ The distance travelled during the entire hour is $63km.$

The speed$-$time graph below displays the trip graphically.

Fill in the blanks.

The maximum speed attained during the trip is $k\frac{m}{h}r.$

The average acceleration of the train during the first $5$ minutes is

$k\frac{m}{h}{r}^2.$