Problem: Poderosa Construction has budgeted $350,000 to build a new clubhouse. They use a mixture of union and nonunion personnel. Grading of the land, electrical, and plumbing work is subcontracted out to union shops. The actual construction of the project, though supervised by union carpenters, is performed mainly by nonunion laborers to conserve costs. Project planning has produced the following chart:
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Immediate Predecessors
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Expected Completion Time (Days)
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A. Grade land
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-
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3
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B. Order building supplies
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-
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4
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C. Hire nonunion labor
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-
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7
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D. Pour concrete slab
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A
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8
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E. Receive organize supplies
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B
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8
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F. Build frame
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C,D,E
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30
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G. Electrical install
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F
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15
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H. Plumbing install
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F
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11
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I. Stucco/paint outside
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H
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20
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J. Dry wall/paint/tile install
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G,H
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18
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K. Finish/cleanup
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I,J
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6
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L. Landscaping
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K
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8
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(Q1) Use the critical path method (CPM) to calculate the earliest start and finish times for all activities (forward pass) and the latest start and finish times for all activities (backward pass).
(Q2) Compute the slack time for each activity and identify the critical activities.
(Q3) Identify all critical path(s). What is the project completion time?
(Q4) How long can the activity (C): “Hire nonunion labor” be delayed without delaying the minimum completion time of the whole project?
(Q5) If activities (D) and (H) are each delayed by 3 days, how long will the whole project be delayed?
(Q6) If activity (K) is delayed by 3 days, how long will the whole project be delayed?
(Q7) If activity (D) is delayed by 1 day (that is the duration of activity (D) changes from 8 days to 9 days and completion times of all other activities remain the same), how many critical paths do we have now in the whole project? What are they?