The following questions are accompanied by three statements (I), (II), and (III). You have to determine which statements(s) is/are sufficient/necessary to answer the questions.

At what time will a train reach city P from city Q?

I. The 600-meter-long train crosses a signal pole in 20 seconds.

II. Another train crosses a 400 m long platform in 30 secs.

III. The train leaves city P at 10 : 00 am for city Q situated at a distance of 1,620 km.