Question 2.4 [3, 2, 1, 2]
Adam is a keen soccer player. One afternoon he decides to practice his kicking skills, and places a
large box 20m away from him. He then kicks the ball at the box and tries to hit it. He decides that he
will only stop once he hits the box ten times. Suppose that the probability of him hitting the box with
any kick is 40%.
a) What is the probability that Adam takes 20 kicks before he can stop?
b) What is the probability that it takes him at least 13 kicks before he can stop?
c) What is the expected value of the number of kicks he will make before he can stop?
d) Based on your answer in (c), would you be surprised if Adam told you it took him 50 kicks
before he hit the box ten times? Why?
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