PERT is a technique to depict project activities and to calculate duration of each activity keeping uncertainty/risk in mind, PERT (Program Evaluation and Review Technique) was first develop in fifties (1950s), as a method to estimate activity duration, it is often referred to as PERT Chart, PERT uses indeterministic methodology to calculate duration, by trying to anticipate three estimates, worst case scenario represented by pessimistic value or longest duration an activity will take to finish, best case scenario represented by optimistic value or shortest duration an activity will take to finish, third factor is the most likely estimate, the 3 factors feed into a formula which takes probability into consideration to calculate the duration of the activity, the formula is: