2.1. A contractor has decided to use project scheduling techniques for the construction of a building. The jobs he has to do are listed in Table 2.1. (a) Draw the precedence constraints graph. (b) Compute the makespan of the project. (c) If it would be possible to shorten one of the jobs by one week, which job should be shortened? Job Description of Job Duration Immediate Predecessor(s) 1 Excavation 2 Foundations 4 weeks 2 weeks 1 3 Floor Joists 3 weeks 2 4 Exterior Plumbing 3 weeks 1 5 Floor 2 weeks 3,4 1 weeks 10 weeks 2 weeks 6 Power On 7 Walls 8 Wiring 9 Communication Lines 1 weeks 10 Inside Plumbing 5 6,7 8 5 weeks 7 11 Windows 2 weeks 10 12 Doors 2 weeks 10 9,10 12,13 13 Sheetrock 3 weeks 5 weeks 4 weeks 14 interior trim 15 exterior trim 12 16 Painting 17 Carpeting 18 Inspection 3 weeks 11,14,15 1 weeks 1 weeks 16 17 Table 2.1. Table for Exercise 2.1