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A train 150 m long, running at a speed of 120 km/hr, will cross a pole on the way in how many seconds?

Time = Distance / SpeedSpeed = 120 km/hr = (120*1000)/3600 m/s Speed = (100/3) m/s

Time = 150/(100/3) = 4.5 sec

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A 150 m long train crosses a bridge of length 250 m in 30 sec. Find the time the train takes to cross a platform 130 m long.

Distance = 150 + 250 = 400 mSpeed = 400/30 = (40/3) m/sec

Next distance = 150 + 130 = 280 mTime taken = 280/(40/3) = 21 sec

A toy train crosses 210 and 122 m long tunnels in 25 and 17 sec respectively. Find the train's length.

Let length of train = x metersSpeed = Distance/TimeFirst distance = 210 + xTime = 25 sec

2nd distance = 122 + xTime = 17 sec

Speed = (210 + x)/25 = (122 + x)/17x = 65 m

A man sitting in a train which is travelling at 50 km/hr observes that a goods train, travelling in the opposite direction, takes 9 sec to pass him. If the goods train is 280 m long, find its speed.

Relative speed = Distance/TimeRelative speed = (280/9) m/sec = 112 km/hrSpeed of goods train = 112 - 50 = 62 km/hr