A runner dashes from the starting line (x = 0) to a point 108 m away and then turns around and runs to a point 18 m away from the starting point in 21 seconds. To the nearest tenth of a m/s what is the average speed?

Answer 1

Find the total distance the runner travels.
- the runner runs 108m
- the runner turns around and runs 108 - 18 = 90m

Find the total time.
- the runner runs the distance in 21s

So the average speed is the total distance over the total time.

(108m + 90m) / 21s = ?

Answer 2

9.43m/s