Suppose that the probability of a baseball player getting a hit in an at-bat is 0.3089. If the player has 25 at-bats during a week, what's the probability that he gets greater than 9 hits?
In general, the probability of getting "x" at-bats is:
(25x)(0.3089)x(1−0.3089)25−x
To find the probability that the player gets greater than 9 hits, we can either substitute x = 9, 10, ..., 25 and add the results OR substitute x = 0, 1, ..., 8, add the results, and subtract that from 1. The rest of the problem boils down to plugging numbers into the calculator.