Demonstrate the crashing steps needed to minimize the cost of crashing down to v

Question

Demonstrate the crashing steps needed to minimize the cost of crashing down to various project lengths. Consider project lengths of 19, 18, 17, 16, 15, and 14 weeks. For each possible step down in project length, specify which activity would be crashed to achieve that length, compute the resultant length of each path in the project, and compute the crashing costs as shown in the table below.(Leave no cells blank - be certain to enter "0" wherever required.)

If the indirect costs for each project duration are $400 (19 weeks), $350 (18 weeks), $300 (17 weeks), $250 (16 weeks), $200 (15 weeks), and $150 (14 weeks), what is the total project cost for each duration?

Explanation / Answer

Activity Predecessor Activity Time ES EF LS LF Slack A None 5 0 5 0 5 0 B A 3 5 8 5 8 0 C A 9 5 14 6 15 1 D A 5 5 10 6 11 1 E B 7 8 15 8 15 0 F D 4 10 14 11 15 1 G C,E,F 4 15 19 15 19 0 ES = E of Tail Event EF = ES + Activity Duration LF = L of Head Event LS = LF - Activity Duration Slack - LS - ES E = Earliest occurrence time for the event L = Latest allowable time for the occurrence of event Paths Weeks Duration A-B-E-G 5+3+7+4 19 A-D-E-G Not A Path NA A-C-G 5+9+4 18 A-D-F-G 5+5+4+4 18 The Critical path is A-B-E-G with estimated duration of 19 weeks Normal Project Length - 19 weeks Activity Normal Time Crash Time Normal Cost Crash Cost Day Reduction Cost Reduction Slope a b c d e = a-b f = d-c f/e A 5 4 $40.00 $80.00 1 $40.00 $40.00 B 3 1 $60.00 $100.00 2 $40.00 $20.00 C 9 6 $50.00 $110.00 3 $60.00 $20.00 D 5 4 $100.00 $180.00 1 $80.00 $80.00 E 7 5 $100.00 $130.00 2 $30.00 $15.00 F 4 3 $80.00 $140.00 1 $60.00 $60.00 G 4 3 $70.00 $130.00 1 $60.00 $60.00 Project Duration 19 weeks 18 weeks 17 weeks 16 weeks 15 weeks 14 weeks Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 A-B-E-G 19 None E A G E B A-C-G 18 None A G C C A-D-F-G 18 None A G F D Crash Cost for this step $0.00 $15.00 $20.00 $60.00 $95.00 $120.00 Cumulative Crash Cost $0.00 $15.00 $35.00 $95.00 $190.00 $310.00 Total Direct Cost $500.00 $515.00 $535.00 $595.00 $690.00 $810.00 1. Stage 1 - Crashing Activity E by 1 week as it has least slope and is on critical path Crash Cost = $15 2. Stage 2 - Crashing Activity A by 1 week as A has next least low slope, being common activity Crash Cost = $20 3. Stage 3 - Crashing Activity G by 1 week as G has next least low slope, being common activity Crash Cost = $60 4. Stage 4 - Crash Activities E, C and F and the related costs are Crash Cost = $15 + $20 + $60 = $95 5. Stage 5 - Crash Activities B, C and D and the related costs are Crash Cost = $20 + $20 + $80 = $120 Duration Direct Cost Indirect Cost Total Cost a b a+b 19 $500.00 $400.00 $900.00 18 $515.00 $350.00 $865.00 17 $535.00 $300.00 $835.00 16 $595.00 $250.00 $845.00 15 $690.00 $200.00 $890.00 14 $810.00 $150.00 $960.00 The least cost is at 17 weeks with $835. Option B

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