# The BETAINV function part 2

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The frequent formulation of the beta distribution is also known as the beta distribution of the first type., while the beta distribution of the second type is an alternative name for the main beta distribution.

The BETAINV The function returns the inverse of the cumulative beta probability density function for a specified beta distribution. In other words, and probability = BETADIST (x, …), subsequently BETAINV (probability, …) = X. The beta distribution can be used in project planning to model probable completion times given an expected completion time and variability.

It should be noted that this function has been superseded by one or more new Excel functions 2010 onwards (BETA.INV) that can provide greater precision and whose names better reflect their use. Even though this feature is still enabled for backward compatibility, you should consider using the new features from now on, since this function may not be available in future versions of Excel.

The BETAINV The function uses the following syntax to operate:

BETAINV (x, alfa, beta, cumulative,[A],[B])

The BETAINV The function has the following arguments:

• probability: required. This represents a probability associated with beta distribution
• alfa: additionally required. This is a parameter of the distribution
• beta: required. This is also a parameter of the distribution
• A: Optional. This is a lower limit for the interval of X
• B: this is also optional. This is an upper limit for the interval of X.

It should be noted at the same time that:

• If any argument is not numeric, BETAINV return the #VALUE! error value
• And alfa ≤ 0 O beta ≤ 0, BETAINV return the #ON ONE! error value
• And probability ≤ 0 O probability > 1, BETAINV return the #ON ONE! error value
• If you omit values ​​for A Y B, BETAINV uses the standard cumulative beta distribution, so that A = 0 Y B = 1.