Deck 9: Project Scheduling: Pertcpm

Question 1

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

Answer 1

False

Question 2

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

Answer 2

True

Question 3

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

Answer 3

True

Question 4

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 5

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

Question 6

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 7

A path through a project network must reach every node.

Question 8

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

Question 9

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

Question 10

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 11

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

Question 12

All activities on a critical path have zero slack time.

Question 13

A critical activity can be part of a noncritical path.

Question 14

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 15

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

Question 16

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

Question 17

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 18

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

Question 19

Activities require time to complete while events do not.

Question 20

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

Question 21

​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 22

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 23

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.

Question 24

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 25

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 26

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 27

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 28

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 29

Arcs in a project network indicate

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

Question 30

Activities with zero slack

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

Question 31

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 32

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 33

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 34

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 35

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 36

Slack equals

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

Question 37

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.

Question 38

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 39

​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 40

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

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

Question 41

A cookie recipe gives the following numbered steps.
1.Preheat oven.
2.Grease cookie sheets.
3.Cream shortening and sugar.
4.Add eggs and flavoring.
5.Measure and sift dry ingredients.
6.Add dry ingredients to mixture.
7.Drop by spoonfuls onto sheets and bake for 10 minutes.
Although the steps are numbered, they do not always reflect immediate precedence relationships. Develop a table that lists the immediate predecessors for each activity.

Question 42

​In PERT, the activity duration time is equal to the

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

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

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 45

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

Question 46

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.
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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.
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Question 47

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

Question 48

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.

Question 49

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 50

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 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 more than 28 weeks more or less than 50%?

Question 52

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 53

​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 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 54

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 55

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 56

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 57

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 58

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 59

​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.