A bus starts from rest at 2:00 PM.The distance covered by the bus at various instants of time are recorded as follows:
Distance[Km];0 10 20 30 40 50
Time[PM]:2.00 2.30 3.00 3.30 4.00 4.30
[a]Draw the distance time graph for this bus.
[b]What distance was covered by the bus at 3.15 PM?

Dear Student
a)

From graph we can conclude
v = d/t = 10km/ 30min =10 km/ 0.5h = 20 km/h
So distance covered by bus in 15 min 
d = 20 x (15 / 60) = 5km
So
Distance covered by the bus at 3.15pm is = Distance covered by bus at 3.00 pm + distance covered by bus in 15 min = 20 + 5= 25 km.

Regards