A 161.5 - m -long train crosses a 758.5 - m -long bridge in 46 seconds. What is the speed of the train? 

Correct option is A

Given:

- Length of train = 161.5 m
- Length of bridge = 758.5 m
- Time taken to cross the bridge = 46 seconds
Formula Used:

- Total distance covered = Length of train + Length of bridge
- Speed = $$\frac{Distance }{ Time}$$​​
- Speed (km/h) = Speed (m/s) × $$\frac{18}{5}$$​​
Solution:

Calculate total distance:
161.5 + 758.5 = 920 meters
Speed in m/s:
$$\frac{920 }{46}$$​ = 20 m/s
Convert speed to km/h:
$$20 × \frac{18}{5 }$$​= 72 km/h
The speed of the train is 72 km/h.