What is the speed of the train? Statement I: The train crosses 150 meters long platform in 45 seconds. Statement II: The train crosses another stationary train of same length in 60 seconds. Statement III: The train crosses a signal pole in 30 seconds.

Statement I alone is insufficient (only platform length and time, no train length). Statement II gives crossing another stationary train of same length in 60 seconds, meaning the train covers twice its length in 60 seconds, so its length L in 30 seconds. Statement III gives crossing a signal pole in 30 seconds (covers L distance). Combining I and III: From III, L = 30×speed. From I: (L+150) = 45×speed. Two equations, two unknowns, so speed can be found. Similarly I and II together are sufficient. Answer: I and either II or III.