Deck 13: Project Scheduling: Pertcpm

Question 1

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 the alternatives are true.

Answer 1

D

Question 2

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.

Answer 2

C

Question 3

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 the alternatives is correct.

Answer 3

B

Question 4

In PERT,the activity duration time is equal to:

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

Question 5

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

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

Question 6

In deciding which activities to crash,one must

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

Question 7

Slack equals

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

Question 8

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

A)Crash only non-critical 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 9

The main difference between CPM and PERT is:

A)the use of 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 10

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 11

When activity times are uncertain,

A)assume they are normally distributed.
B)calculate the expected time, using (a + 4m + b)/6.
C)use the most likely time.
D)calculate the expected time, using (a + m + b)/3.

Question 12

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 13

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 14

Arcs in a project network indicate

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

Question 15

Activities with zero slack

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

Question 16

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 17

Which 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 18

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 19

The critical path

A)is any path that goes from the starting node to the completion node.
B)is a combination of all paths.
C)is the shortest path.
D)is the longest path.

Question 20

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 21

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 22

The earliest finish time for the final activity is the project duration.

Question 23

All activities on a critical path have zero slack time.

Question 24

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

Question 25

A critical activity can be part of a noncritical path.

Question 26

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.

Question 27

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

Question 28

A path through a project network must reach every node.

Question 29

The linear programming model for crashing presented in the textbook assumes that any portion of the activity crash time can be achieved for a corresponding portion of the activity crashing cost.

Question 30

Activities require time to complete while events do not.

Question 31

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

Question 32

Critical activities are those that can be delayed without delaying the entire project.

Question 33

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

Question 34

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

Question 35

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

Question 36

The difference between an activity's earliest finish time and latest finish time equals the difference between its earliest start time and latest start time.

Question 37

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

Question 38

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

Question 39

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

Question 40

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

Question 41

Explain how and why all predecessor activities must be considered when finding the earliest start time.

Question 42

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

Question 43

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 9 hr.?

Question 44

Suppose that,after analyzing a PERT/CPM ntwork,the project manager finds that the project completion time is unacceptable.What are the manager's options?

Question 45

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 46

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. 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 47

Why should projects be monitored after the critical path is found?

Question 48

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

Question 49

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 50

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 51

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

Question 52

Once the earliest and latest times are calculated,how is the critical path determined?

Question 53

From this PERT/CPM network,determine the list of activities and their predecessors.

Question 54

Consider a project that has been modeled as follows:
a.Draw the PERT/CPM network for this project and determine 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 7 hours and activity L was delayed by 4 hours? Explain.

Question 55

Name at least three managerial situations where answers are provided by project management solutions.

Question 56

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 57

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. 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 58

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

Question 59

Explain how and why all successor activities must be considered when finding the latest finish time.

Question 60

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 61

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 62

Mary Yetter,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 the bar code scanner of Example 1.The corporate planning group in San Jose,California has contacted her and has asked how confident the design group is about completing the project in 60 days.She has developed these estimated time durations in days for the project:
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 58 days to complete?
d. Which path in the project network offers the greatest risk of overrunning a new deadline of 56 days?

Question 63

A project has the following activities,durations,costs,and precedence relationships: Develop a cost-time 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.

Question 64

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 65

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 66

Joseph 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 King 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.