In Google Sheets, the function POISSON.DIST(x, mean, cumulative) is used to calculate the Poisson distribution.

It returns the probability of a certain number of events occurring in a fixed interval of time or space, given the average rate of occurrence (mean).

The parameters for the function are as follows:

x: This is the actual number of events you want to calculate the probability for.

mean: This is the average rate at which the events occur in the given interval.

cumulative: This is a logical value (either TRUE or FALSE) that determines the type of probability calculation to perform. If cumulative is TRUE, the function returns the cumulative distribution function (the probability of

observing at most x events). If cumulative is FALSE, the function returns the probability mass function (the probability of observing exactly x events).

Here's an example usage of the function:

=POISSON.DIST(3, 2, TRUE)

This formula calculates the cumulative probability of observing at most 3 events, given an average rate of 2 events.