Best Case Estimate – this would be the optimistic time for a task completion. Probable Case Estimate – most realistic time for task completion. Worst Case Estimate – pessimistic time for a task to be completed. How can a project manager use these concepts to estimate task duration? Traditional PERT techniques use a weighted formula for calculating the estimated duration of each task. The PM first makes three estimates for each task: best case (b), probable (p), and worst case (w). The manager then assigns a weight to each estimate. The weight can vary, but a common approach is to use a ratio of B = 1, P = 4, and W = 1. The expected task duration is calculated as follows: (B + 4P + W) / 6

Answered by alokgupta14 , an ibibo Guru, at 2:09 AM on November 02, 2007