The speed is the change in position divided by the time.
There are four intervals where the speed is uniform:
1) from 0 to 0,5 hours
2) from 0,5 hours to 3 hours
3) from 3 to 4 hours
4) from 4 to 7 hours
We are asked to say the average speed during the interval in which J. is traveling the fastest.
That is where the is more inclined, and that happen in the last interval. There the speed is tha change in position / the time =
(200 -0)miles/3hours = 67 mph.
If you are not sure that this is the fastest speed, you can calculate the speed in the other intervals in the same way and compare.
