The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:

Question: The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:

Solution:
Speed = (45 × 5)/18 m/sec = 25/2 m/sec
Time = 30sec
Let the length of bridge be x metres

Now
(130 + x)/30 = 25/2
260 + 2x = 750
2x = 750 - 260
2x = 490
x = 490/2
x = 245