How long will a train 100m long traveling at 72kmph take to overtake another train 200m long traveling at 54kmph?

Answer 1

The difference in speed is 72-54=18kmph which is converted to meters per second by multiplying by 1000 and dividing by 3600 = 5 m/s. Total distance is 300 metres which is 100+200, so time taken is 300/5=60 seconds or exactly one minute.