Sajal can ride a scooter constantly at a speed of 30 km/hr.

Solution:

We have,

speed $=\frac{\text { distance }}{\text { time }}$

We have the following table for Distance-Time graph
 

 
(i) Given speed = 30 km/hr , distance = 75 km

using formula we have

$30=\frac{75}{\text { time taken }}$

time taken $=2.5 \mathrm{hr}$

Hence, the time taken by Sajal to ride 75 km is 2.5 hr.

(ii) Given speed $=30 \mathrm{~km} / \mathrm{hr}$, time $=3 \frac{1}{2} \mathrm{hr}$

using formula we have,

$30=\frac{\text { distance }}{7 / 2}$

distance $=105 \mathrm{~km}$

Hence, the distance covered by Sajal in $3 \frac{1}{2}$ hours is $105 \mathrm{~km}$.