A train 200 m long is running at a speed of 36 km/hr. It crosses a bridge in 30 sec. What is the length of the bridge?

Speed in m/sec = 36 km/hr x 5/18 = 10m/sec
Distance covered by train in crossing the bridge = Speed of train in m/sec x time in sec = 10 m/sec x 30 sec = 300 m
Now, we know that
Distance covered by train in crossing the bridge= Length of train + Length of bridge
Therefore, Length of bridge = 300m - 200m = 100m