The length of the bridge, which a train 130 meters long and travelling at 45 km/hr can cross in 30 seconds, is
A. 200 m
B. 225 m
C. 245 m
D. 250 m

To find the length of the bridge, we can use the formula for distance, which is:

Distance = Speed × Time

First, let's convert the speed from kilometers per hour to meters per second. There are 1000 meters in a kilometer and 3600 seconds in an hour, so:

Speed = (45 km/hr) × (1000 m/km) / (3600 s/hr) = 12.5 m/s

Now, we know the train travels at 12.5 meters per second, and it crosses the bridge in 30 seconds. The total distance covered in 30 seconds is:

Distance = Speed × Time = 12.5 m/s × 30 s = 375 meters

The total distance includes both the length of the train and the length of the bridge. Since the train is 130 meters long, we can subtract that from the total distance to find the length of the bridge:

Length of Bridge = Total Distance - Length of Train = 375 meters - 130 meters = 245 meters

So, the length of the bridge is 245 meters.

The correct answer is C. 245 m.