Question

A train is booked to do the run between two places 55 km apart,in 1 hr 20 min. if it travels for the first 30 km at 36km per hour, at what speed must it travel for the rest of the distance in order to complete the journey in time​

Answer 1

The train must travel at 50 km/hr to make it on time.

Explanation:

distance to be covered = 55 km

time to cover this distance = 1 hr 20 min

1 hr 20 min = 1.33 hrs (20 min = 20/60 hrs = 0.33 hrs)

The train travels the first 30 km distance at a speed of 36 km/hr

and we know that time taken = distance/speed

therefore the time taken to run this 30 km will be

time = 30/36 = 0.83 hr

The train still has 55 - 30 = 25 km to cover,

and the time left is 1.33 - 0.83 = 0.5 hrs left

to make it on time, the train must travel at

speed = distance/time = 25/0.5 = 50 km/hr