Answer:
<em>The train must travel at 50 km/hr to make it on time.</em>
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Step-by-step 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 = <em>50 km/hr</em>
