Ayúdame hacer este ejercicio
(8-)×(-1)

If you mean "measure" as in mean, median, or mode, then I would say do a mean, which is adding up all the distances he hit the ball, then dividing it by 10 (the number of times he hit the ball) this is the average
I'm not really sure what you mean by "which measure" but i'm guessing this is what would be the closest to your answer.
Or do u mean "measure" as in meters, or inches, or centimeters..?? I'm kind of confused.