A train P travelling at a speed of 15 m/s is able to cross a platform of 200 meter length completely in 30 seconds. Approximately how long will it take train P to cross a man who is coming towards the train on his bike at a speed of27 km/h? [Note: Ignore the length of the bike.]

11.1 sec

Length of train = X km/h

Distance = Speed × Time

= 15 ×  30 = 450 m

Total Distance = Length of train + Length of platform

450 = 200 + X

X =  450 - 200

X = 250 m

Time taken by train to cross a men on bike with speed = 27 km/h

27 km/h = 27 × \(\frac{5}{18}\) m/sec = \(\frac{15}{2}\) = 7.5 m/sec

Relative speed = 15 + 7.5 = 22.5 m/sec

( When moves in same direction )

Time = \(\frac{250}{22.5}\)

= 11.1 sec