Question

Normal Time Crash Time Normal with Activity (weeks) (weeks) Cost Crashing Immediate Predecessor(s) $1,400 A 3 2 $2,050 $2,800 B 2 1 $2,100 1 1 $350 $350 7 $1,400 $1,700 A 6 3 $900 $1,200 $5,000 $2,000 F 2 $4,000 $1,500 C 4 G 2 D, E weeks a) Based on the given information regarding the activities for the project, the project completion date b) To reduce the duration of the project to 10 weeks at the least cost, the following is the order of what needs to be followed while crashing the activities: The first activity to crash is by 2 weeks at a per week crashing cost of dollars. Next, one should crash activity D and activity by 2 weeks for an additional total per week crashing cost of dollars c) New requirements are to reduce the project to 7 weeks. Continuing to crash the activities from 10 weeks based following is the order for crashing: on the above crashing already completed, the by 2 weeks at a per week crashing cost of Next activity to crash in order is dollars Next, one should crash activity and activity E by 1 week at a total per week crashing cost of dollars dollars Total cost of crashing the project to 7 weeks

Answer 1

a) Project completion time is determined by the critical path which is A-D-G = 3+7+4 = 14 weeks

Other path = BEG = 2+6+4 = 12 weeks

b) The project can be shortened by crashing activities on the critical path.

Crashing cost / week= (Crash cost of activity - Normal cost) / Crashed weeks

First activity to crash is D by 2 weeks at lowest per crashing cost of (1700 -1400) / 4 = $75 per week , Total cost at the step = 75*2 = 150 ----(1)

Next we should crash D and G by 2 weeks for an additional total per week cost of 75 + (2000-1500) / 2 = $325 / week , Total cost at the step = 325*2 = 650 ----(2)

c) Now the path ADG is 8 weeks, BEG is 10 weeks

Crash E by 2 weeks at a per week cost of (1200- 900)/ 3= $100 / week, Total cost at the step = 100*2 = 200----(3)

Next, one should crash activity A and activity E by 1 week at total cost per week crashing cost of (2050-1400) / 1 + 100 = $750 , Total cost here = $750----(4)

Total cost of crashing project to 7 weeks= (1) + (2) + (3) + (4) = 150 + 650 + 200 + 750 = $1750