Correct Answer - Option 3 : 200 m
Given:
Length of train = 400 m
Speed of train = 60 km/h
Time to cross the bridge = 36 seconds
Formula used:
Speed = (Length of train + Length of bridge)/Time to cross the bridge
1 km/hr = 5/18 m/s
Calculations:
Let the length of bridge be x.
Speed = (Length of train + Length of bridge)/Time to cross the bridge
⇒ (60 × 5/18) = (400 + x)/36
⇒ 600 = 400 + x
⇒ x = 200 m
∴ The length of bridge is 200 m.