Concept explainers
The estimated times and immediate predecessors for the activities in a project at George Kyparis’s retinal scanning company are given in the following table. Assume that the activity times are independent.
a) Calculate the expected time and variance for each activity.
b) What is the expected completion time of the critical path? What is the expected completion time of the other path in the network?
c) What is the variance of the critical path? What is the variance of the other path in the network?
d) If the time to complete path A–C is
e) If the time to complete path B–D is normally distributed, what is the probability that this path will be finished in 22 weeks or less?
f) Explain why the probability that the critical path will be finished in 22 weeks or less is not necessarily the probability that the project will be finished in 22 weeks or less.
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- Dave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: O Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s) E F A B C D Dave's earliest start (ES) and earliest finish (EF) are: 5 8 00 2 2 Activity HOT G ES Н EF 5 5 5 10 7 B B C, E D.Farrow_forwardDave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s)A 7 - E 4 BB 8 - F 7 BC 4 A G 11 C, ED 1 A H 6 D , F Dave's earliest start (ES) and earliest finish (EF) are: Activity ES EF A 0 7 B 0 8 C 7 11 D 7 88 E 8 12 Part 7 F ? ? G ? ? H ? ?arrow_forwardDave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s) A 7 − E 5 B B 8 − F 6 B C 4 A G 11 C, E D 3 A H 7 D , F Part 2 Dave's earliest start (ES) and earliest finish (EF) are: Part 3 Part 4 Part 5 Part 6 Part 7 Part 8 Part 9 Part 10 Dave's latest start (LS) and latest finish (LF) are:…arrow_forward
- Dave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s) A 7 − E 4 B B 6 − F 5 B C 4 A G 10 C, E D 2 A H 8 D , F Part 2 Dave's earliest start (ES) and earliest finish (EF) are: Part 3 Part 4 Part 5 Part 6 Part 7 Part 8 Part 9 Part 10 Dave's latest start (LS) and latest finish (LF) are:…arrow_forwardDave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s) A B с D 7 8 80 31 3 A A Dave's earliest start (ES) and earliest finish (EF) are: Activity A EFI G H ES EF 7 4 5 11 6 B B C, E D, Farrow_forwardDave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: Dave's earliest start (ES) and earliest finish (EF) are: Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s) A B C D 7 2 A Activity A F G H ES | FF 5 6 9 7 B B C. E D, Farrow_forward
- Dave Fletcher was able to determine the activity times for constructing his laser scanning machine. Fletcher would like to determine ES, EF, LS, LF, and slack for each activity. The total project completion time and the critical path should also be determined. Here are the activity times: Dave's earliest start (ES) and earliest finish (EF) are: Activity Time (weeks) Immediate Predecessor(s) Activity Time (weeks) Immediate Predecessor(s) A B C D 7 6 3 2 A A Activity A ES EFGH EF 7 3 6 11 6 B B C, E D, Farrow_forwardConsider a project that has been modeled as in the table below. Part a) Draw the PERT/CPM network for this project and determine the project’s expected completion time μP and its critical path. Part b) Suppose the standard deviations of the activity durations are σA = 2, σB = 1, σC = 0, σD = 2, σE = 3, and σF = 0. Then please estimate the standard deviation of the overall project’s standard deviation σP . Part c) Suppose for the standard Normal random variable Z, we know P[−1 ≤ Z ≤ +1] ' 68%, P[−2 ≤ Z ≤ +2] ' 95%, and P[−3 ≤ Z ≤ +3] ' 99.7%. Then, approximately what time T is one for which there is only a less than 2.5% chance for the completion time to beat (be shorter than)? *Please answer a-c and type your work and answers or write them neatly please* Thank youarrow_forwardConsider a project that has been modeled as in the table below. Part a) Draw the PERT/CPM network for this project and determine the project’s expected completion time μP and its critical path. Part b) Suppose the standard deviations of the activity durations are σA = 2, σB = 1, σC = 0, σD = 2, σE = 3, and σF = 0. Then please estimate the standard deviation of the overall project’s standard deviation σP . Part c) Suppose for the standard Normal random variable Z, we know P[−1 ≤ Z ≤ +1] ' 68%, P[−2 ≤ Z ≤ +2] ' 95%, and P[−3 ≤ Z ≤ +3] ' 99.7%. Then, approximately what time T is one for which there is only a less than 2.5% chance for the completion time to beat (be shorter than)? *Please answer a-c and either type your work and answers or write them neatly showing each step, please* NO EXCEL Thank you!arrow_forward
- Suppose that the project team has arrived at the following time estimates for activity B (Select site and survey) of the St. John’s Hospital project: a = 7 weeks, m = 8 weeks, and b = 15 weeks a. Calculate the expected time and variance for activity B. b. Calculate the expected time and variance for the other activities in the project.arrow_forwardConsider the project described in the table below: Activity Duration A B C D E F G H 9 4 8 8 5 7 4 6 OEST-9 and LCT = 15 OEST=9 and LCT = 13 Immediate Predecessor What is the earliest start time (EST) and latest completion time (LCT) of activity B? OEST=9 and LCT = 20 OEST-9 and LCT-17 - A A A B B,C C,D E,F,Garrow_forwardA project has the activity duration and cost information indicated in the table where all times are in weeks. What is the total cost for completing this project in 50 days? Activity Predecessor Normal Time Normal Cost Crash Time Crash Cost A -- 8 $12,000 5 $21,000 B A 12 $20,000 9 $30,000 C A 15 $24,000 10 $60,000 D B 3 $10,000 2 $15,000 E C 9 $17,000 6 $34,000 F E 7 $5,000 6 $6,000 G D 8 $14,000 6 $20,000 H A 12 $22,000 10 $30,000 I H 6 $50,000 5 $55,000 J F, G, I 11 $33,000 9 $50,000arrow_forward
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