Find the mean of the given probability distribution. The number of golf balls ordered by customers of a pro shop has the following probability distribution.
x P(x) 3 0.14 6 0.39 9 0.36 12 0.01 15 0.10
x P(x) 3 0.14 6 0.39 9 0.36 12 0.01 15 0.10