Three Point Estimating

Three-Point Estimating is an estimating technique used in Estimate Costs process of Project Cost management process area. This provides accuracy over the single-point activity cost estimates
The three estimates used are
Most likely (M) = Realistic cost estimate of the activity
Optimistic(O) = Best case cost estimate of the activity
Pessimistic (P) = Worst case cost estimate of the activity

The expected Cost using Triangular Distribution
                            (O + M + P)
                C =      ---------------
                                   3

The expected Cost using Beta Distribution 
                          ( O + 4M + P)
               C =       ----------------
                                    6

Sample question.
If it takes 8 hours to build a wall on a normal day and 7 hours if the weather condition is very good and 12 hours if the weather condition is bad. What will be the estimate using Beta Distribution?
C =  (7 + 4 * 8 + 12) /6 = 51/3 = 17

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