# 3.5.3.5.1 Betainv

## Description

Returns the inverse of the cumulative distribution function for a specified beta distribution.The beta distribution is useful in project planning to model probable completion times given an expected completion time and variability.

## Syntax

BETAINV(double probability, double alpha, double beta)

## Parameters

Probability

a probability associated with the beta distribution.

Alpha

The first shape parameter of the distribution.

Beta

The second shape parameter of the distribution

## Return

Returns the inverse of the cumulative distribution function for a specified beta distribution.

## Example

double bb = betainv(0.8975362,8,10);
bb = ;//Should return 0.5928749129231.