This shows the probability associated with each value of X from X=0 to X=n. It is notated by two categories that are identified as A and B. Also included in the definition are the probabilities of A and B which together should equal 1; The number of individuals or observations in the sample, n; the variable X refers to the frequency category A occurs in the sample.

These kinds of distributions tend to be normal distributions, particularly when the sample size, n, is large. The data in these distributions are discrete however, so the normal distribution is only an approximation of this kind of distribution.

Ex. Flipping a coin