BetaPERT Distribution

The BetaPERT distribution is a specialized version of the Beta distribution and is often used for project risk analysis An analysis that focuses on predicting the probability of those (presumably rare) failures that can lead to injury, loss of life, severe damage to the system, or perhaps damage to the surrounding environment.. Mathematically, it is a Beta distribution. While a Generalized Beta Distribution requires four parameters, a BetaPERT requires only three. A particular formula (inherent to the BetaPERT) determines the mean of the distribution (and hence its shape).

By default, it is defined by specifying either a Minimum (0th percentile), Most Likely and Maximum (100th percentile):

Alternatively, if you check the 10% / 90% checkbox, you can specify the 10th percentile, Most Likely and 90th percentile.