how to find the average velocity and speed for an entire postion time graph
(1) Pick the times you want to average over. Call them t2 and t1.
(2) Measure the distance change, x2 - x1.
The average velocity is ((x2 - x1)/(t2 - t1)
(3) The average speed is harder.
You need to plot the instantaneous speed |x'(t)| and average that
I am assuming motion in one dimension on ly. If two or three dimensional, you must use vectors.