Deck 9: Project Scheduling: Pertcpm

Question 1

Crashing refers to an unanticipated delay in a critical path activity that causes the total time to exceed its limit.

Answer 1

False

Question 2

The variance in the project completion time is the sum of the variances of all activities in the project.

Answer 2

False

Question 3

The project manager should monitor the progress of any activity with a large time variance even if the expected time does not identify the activity as a critical activity.

Answer 3

True

Question 4

The normal distribution tends to be a better approximation of the distribution of total time for shorter projects where the critical path has relatively few activities.

Question 5

The earliest start time for an activity is equivalent to the latest of the earliest finish times for all its immediate predecessors.

Question 6

PERT and CPM are applicable only when there is no dependence among activities.

Question 7

Constraints in the LP models for crashing decisions are required to compare the activity's earliest finish time with the earliest finish time of each predecessor.

Question 8

When activity times are uncertain,total project time is normally distributed by considering the overall mean being equal to the sum of the means of all of the critical activities.

Question 9

When activity times are uncertain,an activity's most likely time is the same as its expected time.

Question 10

A key distinction of the critical path is that all activities on the critical path have zero slack time.

Question 11

The final activity's earliest finish time is the anticipated project duration.

Question 12

The earliest start time for an activity is equal to the smallest of the earliest finish times for all its immediate predecessors.

Question 13

Precedence relationships among activities are critical in CPM analysis but not in PERT.

Question 14

Shortening activity times,which is usually accomplished by adding resources to the project,is called crashing.

Question 15

It is possible to have more than one critical path at a time.

Question 16

It is normal for activities on the critical path to be delayed without delaying the entire project.

Question 17

The latest finish time for an activity is the largest of the latest start times for all activities that immediately follow the activity.

Question 18

A path through a project network must reach every node.

Question 19

A critical activity can be part of a noncritical path.

Question 20

The length of time an activity can be delayed without affecting the project completion time is the slack.

Question 21

Arcs in a project network indicate

A)completion times.
B)precedence relationships.
C)activities.
D)the critical path.

Question 22

The main difference between CPM and PERT is

A)CPM and PERT use different activity time estimates.
B)PERT analysis is less expensive to conduct.
C)PERT lends itself to computerization while CPM networks must be constructed manually.
D)CPM integrates time and cost performance while PERT is based solely on time performance.

Question 23

PERT and CPM

A)are most valuable when a small number of activities must be scheduled.
B)have different features and are not applied to the same situation.
C)do not require a chronological relationship among activities.
D)have been combined to develop a procedure that uses the best of each.

Question 24

When activity times are uncertain,

A)we assume they are normally distributed.
B)we start by calculating the optimistic,the most probable,and the pessimistic time estimates.
C)we use the most probable time.
D)we need to obtain at least four time estimates for each activity.

Question 25

Activities following a node

A)can begin as soon as any activity preceding the node has been completed.
B)have an earliest start time equal to the largest of the earliest finish times for all activities entering the node.
C)have a latest start time equal to the largest of the earliest finish times for all activities entering the node.
D)None of these are correct.

Question 26

A critical activity is

A)an activity that consumes no time but shows precedence between events.
B)a milestone accomplishment within the project.
C)an activity with zero slack.
D)the beginning of an event.

Question 27

Activities K,M,and S immediately follow activity H,and their latest start times are 14,18,and 11.The latest finish time for activity H

A)is 11.
B)is 14.
C)is 18.
D)cannot be determined.

Question 28

Activities with zero slack

A)can be delayed.
B)must be completed first.
C)lie on a critical path.
D)have no predecessors.

Question 29

In deciding which activities to crash,one must crash

A)all critical activities.
B)largest-duration activities.
C)lowest-cost activities.
D)activities on the critical path(s)only.

Question 30

Slack equals

A)LF - EF.
B)EF - LF.
C)EF - LS.
D)LF - ES.

Question 31

For an activity with more than one immediate successor activity,its latest finish time is equal to the

A)largest latest finish time among its immediate successors.
B)smallest latest finish time among its immediate successors.
C)largest latest start time among its immediate successors.
D)smallest latest start time among its immediate successors.

Question 32

Activities G,P,and R are the immediate predecessors for activity W.If the earliest finish times for the three are 12,15,and 10,then the earliest start time for W

A)is 10.
B)is 12.
C)is 15.
D)cannot be determined.

Question 33

The earliest start time rule

A)compares the starting times of all activities for successors of an activity.
B)compares the finish times for all immediate predecessors of an activity.
C)determines when the project can begin.
D)determines when the project must begin.

Question 34

Which of the following is a general rule for crashing activities?

A)Crash only noncritical activities.
B)Crash activities with zero slack.
C)Crash activities with the greatest number of predecessors.
D)Crash the path with the fewest activities.

Question 35

Which of the following is NOT a significant challenge of project scheduling?

A)Deadlines exist.
B)Activities are independent.
C)Many employees could be required.
D)Delays are costly.

Question 36

To calculate an activity's latest finish time,you should consider its

A)predecessors' latest finish times.
B)predecessors' latest start times.
C)successors' earliest start times.
D)successors' latest start times.

Question 37

For an activity with more than one immediate predecessor activity,which of the following is used to compute its earliest finish (EF)time?

A)the largest EF among the immediate predecessors
B)the average EF among the immediate predecessors
C)the largest LF among the immediate predecessors
D)the difference in EF among the immediate predecessors

Question 38

We identify the critical path of a project as

A)any path that goes from the starting node to the completion node.
B)the combined time of all paths of the project.
C)the shortest path through the project.
D)the longest path through the project.

Question 39

Which of the following is always true about a critical activity?

A)LS = EF
B)LF = LS
C)ES = LS
D)EF = ES

Question 40

To determine how to crash activity times,

A)normal activity costs and costs under maximum crashing must be known.
B)shortest times with crashing must be known.
C)realize that new paths may become critical.
D)All of these are correct.

Question 41

A project network is shown below.Use a forward and a backward pass to determine the critical path,and then fill out the table below.Activity times are in weeks. ​
Now assume that the times listed are only the expected times instead of being fixed times.Is the probability of being finished in more than 28 weeks more or less than 50%?

Question 42

From this PERT/CPM network,create a list of activities and their predecessors.​

Question 43

The critical path for this network is A - E - F,and the project completion time is 22 weeks. ​
If a deadline of 17 weeks is imposed,give the linear programming model for the crashing decision.

Question 44

Consider a project that has been modeled as follows: ​
a.Draw the PERT/CPM network for this project and determine the project's expected completion time and its critical path.
b.Can activities E and G be performed simultaneously without delaying the minimum project completion time?
c.Can one person perform A,G,and I without delaying the project?
d.By how much can activities G and L be delayed without delaying the entire project?
e.How much would the project be delayed if activity G was delayed by seven hours and activity L was delayed by four hours? Explain.
​

Question 45

A project has the following activities,precedence relationships,and time estimates in weeks:
​ ​
a.Compute the expected time and variance for each activity.
b.Determine the critical path and the expected duration of the project.
c.What is the probability that the project will take longer than 56 weeks to complete?

Question 46

Joe King has ambitions to be mayor of Williston,North Dakota.Joe has determined the breakdown of the steps to the nomination and has estimated normal and crash costs and times for the campaign as follows (times are in weeks). ​ ​
Joe is not a wealthy man and would like to organize a 16-week campaign at minimum cost.Write and solve a linear program to accomplish this task.

Question 47

A project consists of five activities.Naturally,the paint mixing precedes the painting activities.Also,both ceiling painting and floor sanding must be done prior to floor buffing. ​
a.Construct the PERT/CPM network for this problem.
b.What is the expected completion time of this project?
c.What is the probability that the project can be completed within nine hours?
​

Question 48

From this schedule of activities,draw the PERT/CPM network.

Question 49

Consider the following PERT/CPM network with estimated times in weeks.The project is scheduled to begin on May 1. The three-time estimate approach was used to calculate the expected times and the following table gives the variance for each activity: ​
a.Give the expected project completion date and the critical path.
b.By what date are you 99% sure the project will be completed?

Question 50

Use the following network of related activities with their duration times (weeks)to complete a row for each activity under the column headings below.

Question 51

A project network is shown below.Use a forward and a backward pass to determine the critical path,and then fill out the table below.Activity times are in weeks. ​
Now assume that the times listed are only the expected times instead of being fixed times.Is the probability of being finished in fewer than 25 weeks more or less than 50%?
​

Question 52

Use the following network of related activities with their duration times (weeks)to complete a row for each activity under the column headings below.

Question 53

National Oil Company (NATOCO)must plan the shutdown of its Houston refinery for routine preventive maintenance.Each hour of downtime is lost production time and is very costly,so NATOCO wants the maintenance project completed in 22 hours.The PERT network below shows the precedence relationships of the activities involved in the project.The table gives the activity times and costs under normal operations and maximum crashing. ​
NATOCO wants to know the minimum cost of completing the maintenance project within the 22-hour period.Formulate and solve a linear program that will yield this information.​ ​

Question 54

Marcy Fetter,a staff analyst at the Los Angeles plant of Computer Products Corporation,is assigned to the team that is developing the process design for producing an RFID sensor.The corporate planning group in San Jose,California,has contacted her and asked how confident the design group is about completing the project in 60 days.She has developed the following estimated time durations in days for the project:
​ ​
a.Compute the expected time and variance for each activity.
b.Determine the critical path and expected duration of the project.
c.What is the probability that the project will take longer than 58 days to complete?
d.Which path in the project network offers the greatest risk of overrunning a new deadline of 56 days?
​

Question 55

Three paths of a PERT network have these mean durations and variances in weeks:
​ ​
Which path offers the greatest risk of overrunning a contract deadline of 48 weeks?

Question 56

A senior MIS design class project team has developed the following schedule of activities for their project,using their best estimate of completion times.Both written and oral reports are required.Draw the project network.Can they complete the project in the 38 class days remaining until the end of the semester? ​

Question 57

For the project represented below,determine the earliest and latest start and finish times for each activity as well as the expected overall completion time.

Question 58

Use the following network with activities and times estimated in days to answer questions a through
a.What are the critical path activities?
b.What is the expected time to complete the project?
c.
​
c.
What is the probability the project will take more than 28 days to complete?
​

Question 59

In PERT,the activity duration time is equal to the

A)pessimistic time.
B)optimistic time.
C)most likely time.
D)mean duration.

Question 60

A project has the following activities,durations,costs,and precedence relationships:
​ ​
Develop a time-cost trade-off analysis.Detail the steps that you would use to accelerate or crash the project to its minimum duration at the lowest cost.Determine each step's cost and the duration of the project.​