Correct Answer - Option 2 : 15 hours

**Given: **

A 130 m long train crosses a 70 m long tunnel in 20 seconds.

**Formula Used: **

Time = Distance / Speed = [Length of train + Length of Tunnel] / Relative Speed

And Relative Speed (RS) = Speed of train + Speed of tunnel

**Calculation:**

RS = Speed of train (∵ Speed of tunnel = 0)

Time = [Length of faster train + Length of tunnel] / Relative Speed

⇒ 20 = [130 + 70] / Speed of train

⇒ Speed of train = 10 m/s = 10 × 18/5 km/h = 36 km/h

Time taken by the train to cover the distance of 540 km is 540km / 36 kmph

⇒ 15 hours.

**∴ The required time is 15 hours.**