A scooterist travels along a straight road in two stages and then returns to the starting point.
(i) In the first stage he rides 300m east in 25s. In the second stage he rides another 180m east in 15s. Calculate his average speed and average velocity for the first two stages taken together.
(ii) Immediately after the second stage he turns around and rides back the entire 480m to the starting point in 40s. Find his average speed and average velocity for the whole trip (all three stages together).
(iii) Compare the magnitudes obtained in parts (i) and (ii) and state one inference about how direction of motion affects average velocity but not average speed.