What is BETA.INV function in Excel? BETA.INV function is one of Statistical functions in Microsoft Excel that returns the inverse of the beta cumulative probability density function (BETA.DIST). If probability = BETA.DIST(x,…TRUE), then BETA.INV(probability,…) = x. The beta distribution can be used in project planning to model probable completion times given an expected completion time and variability. Syntax of BETA.INV function…