Question

a train travels the first 30 km of 120 m track with uniform speed of 30 km/hr . what should be the speed of train to cover the remaining distance of track si that its average speed is 60km/hr for entire trip .

Answer 1

total distance = 120km
avg speed = 60km/h
so total time = 2hours

case i
dis. = 30km speed = 30km/h
so time taken = 1 hour

so remaining dis is 90km time = 2-1=1 hour
so speed = 90km/h