s unit of time for activity completion. Due to the fact that PERT has to deal with uncertainty in the activity completion time, it usually includes three time estimates for every activity: optimistic time (the shortest period of time in which the activity can be performed; there is a 1% chance that the activity will be performed within the optimistic time3), most likely time (the completion time with the highest probability) and pessimistic time (the longest time for performing an activity). This step is followed by another: determining the critical path, which can be determined by adding each activity's time and learning the longest path i
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