2. (a) Using PERT, calculate expected project duration and determine the critical path in the network defined by the data below. (b) What is the probability of completing this project in 32 weeks or less? Note: partial diagram is given below to start with. Activity Type 3 Activity # 10 20 30 40 50 60 70 80 90 100 110 120 130 140 Prefab Wall Forms Excavate Cols and Walls Let Elec and Mech Subcontract Deliver wall Forms Forms, Pour & Cure Wall & Col Fig Rough-in Plumbing Install Conduit Erect Wall Forms & Steel Fabricate & Set Interior Column Erect Temporary Roof Pour, Cure & Strip Walls Pour, Cure & Strip Int. Walls Backfill for Slab on Grade Grade & Pour Floor Slab constant constant ta, tm, tb constant ta, tm, tb ta, tm, to ta, tm, to constant constant ta, tm, to constant constant constant constant Duration (weeks) 2 3 3,4,8 4 6,7,8 5, 7, 10 9, 11, 15 9 6 12, 16, 18 10 6 1 5 Followed by Activity # 40 50, 60, 70 60, 70 80, 90, 100 80, 90, 100 110 110 110 120 140 130 140 140 END 10 2 ST 20 3 140 5 END 30 4.5