Correct Answer - Option 1 : 31 second

**Given:**

The length of train = 153 m

The length of bridge = 622 m

Speed of train = 90 km/h

**Formula used:**

S = D/T

Where,

S = Speed

D = Total distance

T = Time

**Calculation:**

According to the question:

Total distance = length of train + length of bridge

⇒ D = 153 + 622

⇒ D = 775 m

S = 90 km/h

⇒ S = 90 × (5/18) m/s

⇒ S = 25 m/s

Now,

S = D/T

⇒ 25 = 775/T

⇒ T = 775/25

⇒ T = 31 second

**∴ The time taken by train to cross the bridge is 31 second.**

1) 1 km/h = (5/18) m/s

2) 1 m/s = (18/5) km/h