A train travels from A to B, a distance of 20,000 m, taking 1,000 s. The journey has three stages. In the first stage the train starts from rest at A and accelerates uniformly until its speed is V m/s. In the second stage the train travels at constant speed V m/s for 600 s. During the third stage of the journey the train decelerates uniformly, coming to rest at B.

1. Sketch the velocity-time graph for the train’s journey.
2. Find the value of V.
3. Given that the acceleration of the train during the first stage of the journey is 0.15 m/s², find the distance travelled by the train during the third stage of the journey.