Binomial Random Variable

A binomial random variable is a variable which only has two possible outcomes, like a coin flip. The outcomes of such a variable are often simplified to "success" and "failure."

Binomial Probability Function

When the probability of success, p, is constant and the trials are independent, the binomial probability function can be taken off the shelf to determine the probability of x successes in n trials.

p(x) = (number of ways to choose x from n)p^x(1-p)^n-x

More technically: