Probability and standard deviation

Question

You and a friend are working on shooting free throws at basketball practice. Your friend has a season average of making 80% of his shots.

a. If the coach asks your friend to shoot 70 times, how many shots do you expect him to make, on average?

b. What is the standard deviation of the number of shots made out of 70?

c. Your friend makes 60 out of 70 shots and is ready to tell the coach that he is improving. The graph below shows a simulation of this distribution. Using both your answers to (a) and (b) and this graph, explain whether or not the coach should have confidence in his improvement.

Answer 1

a. n = 70, p = 0.8, on average make 70 * 0.8 = 56 shots

b. standard deviation = sqrt(70 * 0.8 * 0.2) = 3.35

c. can't answer this without seeing the graph of which you speak.