Question

On a track of length 100km.The train covers first 30 km with a constant speed of 30km/hr. What should be speed of train for next 70km so that average speed of train remains 50km/hr entire trip

Answer 1

d = 100km
initial d = 30km also, u = 30km/h
Average speed = u+v/2
50 = 30+v/2
100 = 30+v
v = 70km/h

Answer 2

Distance=100km

Initial distance=30km

Also,u=30km/h

Average speed=u+v/2

50=30+v/2

100=30+v

V=70km/h