# Excel Functions Related to Poisson & Hypergeometric Distributions

POISSON.DIST($x,\mu,FALSE$)

The Poisson probability of seeing $x$ occurrences in some well-defined interval when $\mu$ occurrences are expected (i.e., the mean number of occurrences is $\mu$). The last argument indicates that the probability returned should not be cumulative.

POISSON.DIST($x,\mu,TRUE$)

The Poisson probability of seeing $x$ or fewer occurrences in some well-defined interval when $\mu$ occurrences are expected (i.e., the mean number of occurrences is $\mu$). The last argument indicates that the probability is cumulative. That is to say, it gives the sum $P(0) + P(1) + \cdots + P(x)$.

HYPGEOM.DIST($x,k,m,N,FALSE$)

The Hypergeometric probability of seeing exactly $x$ white balls when drawing $k$ balls from an urn containing $N$ balls, $m$ of which are white. The last argument indicates that the probability returned should not be cumulative.

HYPGEOM.DIST($x,k,m,N,TRUE$)

The Hypergeometric probability of seeing exactly $x$ or fewer white balls when drawing $k$ balls from an urn containing $N$ balls, $m$ of which are white. The last argument indicates that the probability is cumulative. That is to say, it gives the sum $P(0) + P(1) + \cdots + P(x)$.