Well, as far as I can tell, the mean (average) is the best representation of the data because there is no outlier (a number a lot higher or lower than the rest of the numbers that throws the data off).
Answer:
11) 0.6
12) The maximum height of the ball was 2[ seconds] after it was thrown (I am assuming because the answers are cut off a bit.)
13) $2.50
14) (2,-15)
15) I don't know, since I can't see all the graphs and options. But I want to say the sideways parabola, or the only one shown in the image given
100%-20%=80%
25×80%=20. As a result, Kyle pays $20 for the shirt. Hope it help!