posted by Joe on .
In a survey, 63% of Americans said they own an answering machine. If 14 Americans are selected at random, find the probability that exactly 9 own an answering machine.
Use a binomial probability function table. Values to look up are: p = .63, n = 14, and x = 9.
Calculate it by hand:
P(x) = (nCx)(p^x)[q^(n-x)]
...where q = 1 - p.