Chapter 6: Project Time Management

(Questions and Exercises are derived or transcribed from my copies of

Head First PMP, Greene & Stellman and from PMP Exam Prep, Rita Mulcahy)QUESTION 1

Youre the project manager for a highway construction project. Youve analyzed the work that has to be done and come up with a list of activities. You consulted with the project sponsor in order to find out any important milestones you need to meet. Whats the next thing that you do?

A. Create the project schedule

B. Perform the activity definition process

C. Consult your project management plan to figure out how to handle any schedule change

D. Figure out the dependencies between activities and create a network diagramFOR QUESTIONS 2-4Kathleen is planning Rebeccas wedding.QUESTION 2

Kathleen guesses that 70% of the invitees will RSVP. Instead of waiting for all of the RSVPs to come in, she goes ahead and reserves the tables and chairs now. What is she doing?

A. Compressing the critical path

B. Fast-tracking the project

C. Crashing the schedule

D. Balancing the plan

QUESTION 3

Rebecca is taking a really long time to choose the decorations so Kathleen brings in a professional decorator to help. What is she doing?

A. Compressing the critical path

B. Fast-tracking the project

C. Crashing the schedule

D. Balancing the plan

QUESTION 4

Kathleen needs to get the invitations out quickly, so she hires two temps to come in and help her stuff envelopes. What is she doing?

A. Compressing the critical path

B. Fast-tracking the project

C. Crashing the schedule

D. Balancing the plan

EXERCISE 1

a) For each activity, complete the chart for Expected Duration using the three point estimation formula (pg 150, 6.4.2.4). For extra credit, for each activity,

b) calculate the standard deviation = (P-O)/6, c) the variance = ((P-O)/6))**2 (deviation squared) d) and the estimate range (Expected plus or minus the standard deviation)e) Do (b), (c) and (d) for the Project (the sum of all activities)

RULE: You can never add standard deviations to get the standard deviation of the series. You must first add the variances, and then take the square root of that value.

ActivityOMPExpected DurationActivity Standard DeviationActivity VarianceEstimate Range

A142747

B416089

C394448

D293742

All (A+B+C+D)------

EXERCISE 2

Draw a PDM diagram for this list of nodes:

NODE NAMEPREDECESSORNODE NAMEPREDECESSOR

START--FB

ASTARTGC,F

BAHD

CBIH

DSTARTENDG,I

ED

EXERCISE 3

For this PDM,

a) Find the critical pathb) Find the duration of the critical pathc) Find the total number of pathsd) Find the duration of all non-critical paths

e) Find the float for each activity(The activity duration is the number and the activity is the letter in each box.)

EXERCISE 4

Draw an ADM diagram for this list of nodes:

NODE DUMMY?NODEDUMMY?

START-1no5-4no

1-2no4-3no

1-4YES3-ENDno

2-3YES5-6no

START-5no6-ENDno

EXERCISE 5

For this ADM,

a) Find the critical path, b) Find the duration of the critical pathc) Find the total number of paths

d) Find the duration of all non-critical paths

EXERCISE 6Draw an ADM diagram for this list of nodes:

ACTIVITYESTIMATEACTIVITYESTIMATE

START-A3C-D2

START-B9C-E1

A-C3E-END4

B-CDUMMYD-END2

B-E2

EXERCISE 7For this ADM,

a) Find the critical path

b) Find the duration of the critical path

c) How many non-critical paths are there?

d) Find the duration of all non-critical paths

e) If the duration of Activity C-E changes to 2, what is the effect on the project?f) What activity / activities must be completed before Activity C-D begins?g) If management tells you to complete the project two weeks early, what is the project float? Does the critical path change?

EXERCISE 8For this PDM,

a) Find all early start and early finishb) Find all latest start and latest finish(The activity duration is the number and the activity is the letter in each box.)

ANSWER QUESTION 1D, figure out the dependencies between activities and create a network diagram because analyzed the work means youve used decomposition and created an activity list. These are both part of the Activity Definition process. And milestones that you need means its an input youve seen before. So answer D describes Activity Sequencing, which happens after Activity Definition and takes the Activity List and Milestone List as inputs.Its not A, create the project schedule, because the Schedule Development process needs more than an activity list and resource availability.

And not B, perform the activity definition process, since youve already done the Activity Definition process as given in the question.

And not C, consult your project management plan to figure out how to handle any schedule changes because you only do this during Schedule Control, but since theres no schedule yet, theres nothing to control.

ANSWER QUESTION 2

B. Fast-tracking the project. She is starting a dependent activity before the predecessor has finished. Fast tracking does not add cost. It adds risk.

ANSWER QUESTION 3

C. Crashing the schedule. She is bringing in more resources. Crashing always adds cost. It can reduce but not eliminate risk.

ANSWER QUESTION 4

C. Crashing the schedule. She is bringing in more resources. Crashing always adds cost. It can reduce risk but does not eliminate risk.

ANSWER EXERCISE 1ActivityOMPa) Expected Duration

(P+4M+O)/6b) Activity Standard Deviation

(P-O)/6c) Activity Variance

((P-O)/6))**2d) Estimate Range

A14274728.1675.50030.25022.667 to 33.667

B41608961.6678.00064.00053.667 to 69.667

C39444843.8331.5002.25042.333 to 45.333

D29374236.5002.1674.69434.333 to 38.667

All

e)170.16710.060101.194160.107 to 180.226

170.167 = Sum of expected durations

101.194 = Sum of variances, so 10.060 = square root of 101.194

ANSWER EXERCISE 2

See the diagram for Exercise 3. You could not know the durations from the table, but the diagram shows the correct dependencies.ANSWER EXERCISE 3a) Critical Path = START D E F G ENDb) Duration of Critical Path = 5 + 4 + 6 + 2 = 17c) Total Number of Paths = 3d) Non-critical paths and durations:

1. START A B C G END, Duration: 4 + 3 + 1 + 2 = 10

2. START D H I END, Duration: 5 + 4 + 2 = 11

e) Float:1. D, E, F, G = float 0

2. H, I = float 6

3. A,B,C = float 7

Calculating Float:

Critical Path (longest): Duration = 17, Float is always 0 for critical path

#2 is second longest with duration = 11. D was already counted in critical path. Float for remaining activities = critical path duration (17) minus this path duration (11) which is 6. So Float for H and I is 6.

#1 is third longest with duration = 10. G was already counted in critical path. Float for remaining activities = critical path duration (17) minus this path duration (10) which is 7. So Float for A, B and C is 7.

Critical Path = 17,

Float = 0

D,E,F,GNext longest path = 11

Float = critical-11 = 17-11 = 6D,H,INext longest path = 10

Float = critical-11 = 17-10 = 7

A,B,C,G

A7

B7

C7

D0(already assigned column 1)

E0

F0

G0(already assigned column 1)

H6

I6

ANSWER EXERCISE 4

See the diagram for Exercise 5. You could not know the durations from the table, but the diagram shows the correct dependencies.

ANSWER EXERCISE 5a) Critical Path = START-5, 5- 4, 4-3, 3-ENDb) Duration of Critical Path = 1 + 4 + 1 + 5 = 11c) Total Number of Paths = 4

f) Non-critical paths and durations:

1. START-1, 1-2, 2-3, 3-END Duration: 2 + 3 + (dummy) + 5 = 10

2. START-1, 1-4, 4-3, 3-END Duration: 2 + (dummy) + 1 + 5 = 8

3. START-5, 5-6, 6-END Duration: 1 + 5 + 1 = 7

ANSWER EXERCISE 6See the diagram for Exercise 7. This time you should be able to put in the durations.ANSWER EXERCISE 7

a) The critical path is START-B, B-E, E-END

b) Duration of critical path = 9 + 2 + 4 = 15

c) Total Number of Paths = 5 (Did you find all 5?)

d) Non-critical paths and durations

a. START-A, A-C, C-D, D-END, Duration: 3 + 3 + 2 + 2 = 10

b. START-A, A-C, C-E, E-END, Duration: 3 + 3 + 1 + 4 = 11

c. START-B, B-C, C-E, E-END, Duration: 9 + (dummy) + 1 + 4 = 14

d. START-B, B-C, C-D, D-END, Duration: 9 + (dummy) + 2 + 2 = 13

e) If C-E changes from 1 to 2, the critical path(s) and durations would be:

a. START-B, B-E, E-END, Duration: 15

b. START-B, B-C, C-E, E-END, Duration: 15

Yes, you can have more than one critical path. What is the effect on the project? The project is riskier. Always check for a second or more critical path whenever you answer a question that changes the critical path.

f) START-A, A-C, and START-B. Remember, B-C is a dummy, not an activity.g) The project float is -2 and the critical path would not change. The question is about PROJECT float. Project float compares the project length to an external due date.

There is an assumption on the exam that the project was on time before any situation described in the exam question. At that time, there was a zero project float. Asking for a due date 2 weeks sooner makes the project two weeks late, so you now have a -2 weeks float. Yes, you can have a negative float if the project is behind an imposed external date, or when an activity is late, etc.ANWER EXERCISE 8(The activity duration is the number and the activity is the letter in each box)

Critical path is the path with darker/thicker arrows

Upper left corner of box is earliest start (ES) Upper right corner of box is earliest finish

Lower left corner of box is latest start

Lower left corner of box is latest finish

Float is Latest Earliest, either LS-ES or LF-EF.

I start with 0 as the initial value from start so that I end with the critical path value. Or you can start with 1. Just be consistent.

Calculating Earliest values:Start with critical path going forward, followed by other paths going forward

Calculate Earliest Start first, then Earliest FinishES = previous activity EF + previous activity floatEF = current activity ES + current activity durationActivityDurationFloatESEF

A30Start = 0ES(a) + D(a) = 0+3 = 3

B30EF(a) + F(a) = 3+0 = 3ES(b) + D(b) = 3+3 = 6

D80EF(b) + F(b) = 6+0 = 6ES(d) + D(d) = 6+8 = 14

E40EF(d) + F(d) = 14+0 = 14ES(e) + D(e) = 14+4 = 18

C65EF(a) + F(a) = 3+0 = 3ES(c) + D(c) = 3+6 = 9

Calculating Latest values:

Start with critical path going backward, followed by other paths going backwardCalculate Latest Finish first, then Latest StartLF = previous activity LS previous activity float

LS = current activity LF current activity duration

ActivityDurationFloatLFLS

E40End = 18LF(e) D(e) = 18-4 = 14

D80LS(e) F(e) = 14-0 = 14LF(d) D(d) = 14-8 = 6

B30LS(d) F(d) = 6-0 = 6LF(b) D(b) = 6-3 = 3

A30LS(b) F(b) = 3-0 = 3LF(a) D(a) = 3-3 = 0

C65LS(e) F(e) = 14-0 = 14LF(c) D(c) = 14-6 = 8

3

B

1

C

2

G

4

A

Start

End

6

F

4

E

5

D

4

H

2

I

C

5 wks

B

3 wks

2

A

2 wks

3

1

F

1 wk

End

D

1 wk

E

4 wks

G

5 wks

F

1 wk

4

6

5

Start

2 wks

3 wks

C

3 wks

D

A

1 wk

End

9 wks

3

B

2 wks

4 wks

8

D

E

B

Start

2 wks

ES | | EF

Duration

Activity

Float

LS| | LF

3

A

Start

End

Start

End

3 | | 6

3

B

0

3 | | 6

6

C

0 | | 3

3

A

0

0 | | 3

4

E

6 | |14

8

D

0

6 | |14

14 | |18

4

E

0

14 | |18

3 | | 9

6

C

5

8 | |14

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