Correct Answer - Option 4 : 27 seconds

**Given:**

Length of a train is 150 m

Speed of a train is 60km/hr

Length of a bridge is 300 m

**Formula Used:**

Speed = Distance/Time

**Calculation:**

We know that,

km/hr × 5/18 = m/sec

⇒ 60 × 5/18 = 50/3 m/sec

Total distance to cover,

⇒ 150 + 300

⇒ 450 m

Using the formula,

⇒ 50/3 = 450/Time

⇒ Time = (450 × 3)/50

⇒ Time = 27 sec.

**∴ Time required to cross the bridge is 27 seconds.**