# POISSON.DIST

## Content

This function returns the Poisson distribution.

## Syntax

`POISSON.DIST(nevents, mean, cumulative)`

## Remarks

This function has these arguments:

| Argument | Description |
| -------- | ----------- |
| *nevents* | [Required] Number of events; provide an integer, or the value is truncated; the number must be greater than zero |
| *mean* | [Required] Expected numeric value; the number must be greater than zero |
| *cumulative* | [Required] Set to TRUE to return the cumulative Poisson probability that the number of random events occurring is between zero and n*events* inclusive. Set to FALSE to return the Poisson probability mass function that the number of events occurring is exactly *nevents*. |

## Remarks

The cumulative Poisson probability is calculated as follows:
![](https://cdn.mescius.io/document-site-files/images/8d606653-16a0-474d-b9dc-e2b4d01c2446/images/Func-POISSON-True.png)
The Poisson probability mass function is calculated as follows:
![](https://cdn.mescius.io/document-site-files/images/8d606653-16a0-474d-b9dc-e2b4d01c2446/images/Func-POISSON-False.png)
where x is the number of events (*nevents* argument), mu is the mean ( *mean* argument).

## Examples

`POISSON.DIST(A3,B4,TRUE)`
`POISSON.DIST(R1C2,3,FALSE)`
`POISSON.DIST(7,4,TRUE)` gives the result 0.9488663842071525
`POISSON.DIST(7,4,FALSE)` gives the result 0.059540362609726345