Answers

2014-08-25T07:31:44+05:30
As to pass the man standing on the platform the train has to travel 200m (length of the train) 
72 * 1000/3600
72 * 5/18
4 * 5
20 m/s
Therefore the train takes 1 second to travel 20m
Therefore to travel 200m the train will take 10 second
As to pass the platform 400m long the train has to travel 600m (length of the train + length of the platform)
Therefore to travel 600m with a speed of 20m/s the train will take 30second...

The formula used here is SPEED = DISTANCE/TIME
Therefore ...................   TIME = DISTANCE/SPEED
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The Brainliest Answer!
2014-08-25T09:32:59+05:30
Length of the train = 200m
72km/hr = 72 * 5/18
= 20m/sec
1) Time  = Distance/Speed
             = 200/20
             = 10 sec
It will take 10 seconds to pass the man standing on the platform .
2) Time = Distance/Speed
            = 600/20 (600 = Length of the train + Length of the platform)
            = 30 sec
It will take 30 seconds to pass the platform which is 400m long.
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