Explanation:

- Train A's speed is 54 km/hr.

- It crosses a platform equal to its length in 36 seconds.

- Distance covered by Train A = Speed × Time = 36 × (54 × 1000 / 3600) = 540 meters.

- Therefore, the length of Train A = 540 / 2 = 270 meters (since it equals the platform).

- Train B is 230 meters long and takes 25 seconds to cross the same length platform.

- Total distance covered by Train B = 230 + 270 = 500 meters.

- Speed of Train B = Total distance / Time = 500 / 25 = 20 m/s = (20 × 3600) / 1000 km/hr = 72 km/hr.

- The correct answer is Option:2 - 72 km/hr.