1. Look at the graph. find 4000 km on the distance scale and drop a vertical line from that point to the P wave. Draw a horizontal line from that point to the time scale. This is the time that the P wave takes to travel 4000 km.
2. Do the same for the S wave.
3. The difference in arrival times is the difference between answer 1 and 2.
3. Use the same method recommended by the question. Get a piece of paper. Mark on the paper the points 0 and 5.5 min on the time scale. Slide this paper across the graph and stop where the two points touch the P wave and the S wave. Then drop a vertical line from these 2 points onto the distance scale. This is the distance to the epicentre. Since the distance in the question is in whole number, you should express your answer in whole number.