Hi everyone,
Couple of months the PMI made free PMP exam, there was a question that seems incomplete,
I’ll share the question and the answer here for you opinions ;
a project manager learns that, due to supplier delays, task I should start 10 days after the start of task H. the project manager produces a network diagram where each task has three day duration, and re evaluates the critical path. what is the new critical path?
• A-B-C-D-E
• H-F-G
• H-C-D-E
• H-I-J
Correct answer: H-I-J
The critical path is the longest path throughout the logical network. In this case it is 10d+ 3d + 3d = 16d
How could the two tasks H&I with start to start relationship and put them in the same path?? Saving Changes...
Ghada AsfourRiyadh, Saudi Arabia / Riyadh Region /Ri, Saudi Arabia
Jul 06, 2020 3:15 PM
Replying to Vladimir Liberzon
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I understood that all relationships do not have any lags except the dependency between H and I that is SS+10 days.
So the duration of H-I-J path is 16 days and maximal duration of other paths is 15 days (if all dependencies are FS).
So path H-I-J is critical.
This is the point ; you didn’t include duration for activity H since it is SS with activity I... Saving Changes...
Ghada AsfourRiyadh, Saudi Arabia / Riyadh Region /Ri, Saudi Arabia
Jul 06, 2020 2:57 PM
Replying to Keith Novak
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You didn't provide the duration of the tasks. Your addition shows 2 activities and 1 lag, but there are 3 activities. (edit: I didn't see that all tasks have 3 days duration)
If the question is about what items are on the critical path as stated, then you have only one possible answer because H and I must be included. If the question is about how long is the critical path, you need the duration and dependencies of all 3 tasks, and you lack sufficient information. J can start at any time if there are no dependencies.
I included the answer as it is.
This is the correct answer according to the pmi since this exam was sent by the pmi as a free practice exam.
The question and the answer as it is written Saving Changes...
Vladimir LiberzonR&D Director| Spider Project TeamMoscow, Russian Federation
Yes, you are right. I did not include the duration of activity H since the dependency is SS+Lag. But activity H belongs to the Critical Path.
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2 replies by Ghada Asfour and Keith Novak
Jul 07, 2020 11:11 AM
Ghada Asfour
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Thanks a lot ,,,,
Jul 07, 2020 9:15 PM
Keith Novak
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If there are no constraints on J, it can be done at any time and the critical path is (10 days lag after the start of H) + (3 days for task I) which = 13 days. It's not mentioned, just like A, B, C, D, E, F & G, none of which are included in the critical path duration. The only way it would factor in is if J took longer than 13 days in which case that sole event would be the critical path.
Being the answer provided by PMI doesn't necessarily make it correct. In this case it just means that they didn't catch their own error.
Saving Changes...
Ghada AsfourRiyadh, Saudi Arabia / Riyadh Region /Ri, Saudi Arabia
Jul 06, 2020 5:18 PM
Replying to Vladimir Liberzon
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Yes, you are right. I did not include the duration of activity H since the dependency is SS+Lag. But activity H belongs to the Critical Path.
Yes, you are right. I did not include the duration of activity H since the dependency is SS+Lag. But activity H belongs to the Critical Path.
If there are no constraints on J, it can be done at any time and the critical path is (10 days lag after the start of H) + (3 days for task I) which = 13 days. It's not mentioned, just like A, B, C, D, E, F & G, none of which are included in the critical path duration. The only way it would factor in is if J took longer than 13 days in which case that sole event would be the critical path.
Being the answer provided by PMI doesn't necessarily make it correct. In this case it just means that they didn't catch their own error.
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2 replies by Thomas Walenta and Vladimir Liberzon
Jul 07, 2020 9:53 PM
Thomas Walenta
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The constraint on J is that it is successor of I, as indicated in the sequence, A basic assuption would be that any relationship defaults to FS without lead or lag, unless stated otherwise.
Jul 08, 2020 4:46 AM
Vladimir Liberzon
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Activity I can start no earlier than Start of activity H +10 days and can finish no earlier than on the end of 13th day since the project start. Activity J follows activity I with FS relationship and so can start on the 14th day and finish on the end of 16th day.
All activities have the same 3 days duration, all dependencies except H - I are FS without lags.
Saving Changes...
Thomas WalentaGlobal Project Economy ExpertHackenheim, Germany
Jul 07, 2020 9:15 PM
Replying to Keith Novak
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If there are no constraints on J, it can be done at any time and the critical path is (10 days lag after the start of H) + (3 days for task I) which = 13 days. It's not mentioned, just like A, B, C, D, E, F & G, none of which are included in the critical path duration. The only way it would factor in is if J took longer than 13 days in which case that sole event would be the critical path.
Being the answer provided by PMI doesn't necessarily make it correct. In this case it just means that they didn't catch their own error.
The constraint on J is that it is successor of I, as indicated in the sequence, A basic assuption would be that any relationship defaults to FS without lead or lag, unless stated otherwise. Saving Changes...
Thomas WalentaGlobal Project Economy ExpertHackenheim, Germany
Jul 06, 2020 1:23 PM
Replying to Ghada Asfour
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But if the relationship between the two activities is SS or FF , they will not be in the same path.
What is the definition of a path?
Any sequence of tasks from start to end, regardless of the type of sequence. There are 4 types. Saving Changes...
Vladimir LiberzonR&D Director| Spider Project TeamMoscow, Russian Federation
Jul 07, 2020 9:15 PM
Replying to Keith Novak
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If there are no constraints on J, it can be done at any time and the critical path is (10 days lag after the start of H) + (3 days for task I) which = 13 days. It's not mentioned, just like A, B, C, D, E, F & G, none of which are included in the critical path duration. The only way it would factor in is if J took longer than 13 days in which case that sole event would be the critical path.
Being the answer provided by PMI doesn't necessarily make it correct. In this case it just means that they didn't catch their own error.
Activity I can start no earlier than Start of activity H +10 days and can finish no earlier than on the end of 13th day since the project start. Activity J follows activity I with FS relationship and so can start on the 14th day and finish on the end of 16th day.
All activities have the same 3 days duration, all dependencies except H - I are FS without lags. Saving Changes...
Stating that J follows I FtS is an assumption by the reader. It is nowhere stated in the question itself. As a test taking strategy, I would never do that unless none of the answers make sense.
Using the notation they've provided of a list of letters in alphabetical order, there is no way to denote parallel activity without stating the dependencies explicitly. Dependencies must be provided for exactly that reason.
In a real network diagram, there are often many parallel activities on the critical path. In fact there are often multiple critical paths. The notation "I" itself could be a high level summary of an entire chain of events necessary to create some deliverable. Even assuming that there is some deeper meaning in the alphabetical order is a bad assumption. When creating an actual network diagram, you can create all the nodes arbitrarily as a list, and then sequence them. Labels like letters or numbers are just shorthand titles that fit in boxes easier. Saving Changes...
Thomas WalentaGlobal Project Economy ExpertHackenheim, Germany
Experience shows that most dependencies indeed are FS. The PMP does not only test for literally PMBoK, but requires some experience of the candidate. Making assumptions is a fact of life and certainly project management.
One testing strategy is to choose the least bad answer.
Another is to eliminate answers which are not deductible from the question (like the first 3).
We often struggle to accept an answer if we look for a logical deduction of it, without finding a stringent logic.
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1 reply by Keith Novak
Jul 09, 2020 12:51 PM
Keith Novak
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I sort of agree. We tend to schedule things FtS as it is both the least complex when managing schedules, and it has the least risk.
When tasks are done in parallel where the outcome of one may impact the other, there is risk that some change in one will require rework to the other. For example, if one team is working on tooling for a product based on a preliminary design, a design change may require altering or even scrapping the in-work tooling.
The No-Risk schedule often doesn't fit within the required timeframe so we have to either crash the schedule or fast-track it. When we start asking the question, "Do we really have to complete A before we can start B?" the answer is no, and we re-arrange items on the network diagram.
Although in an ideal world with little schedule pressure, we would like to assume most tasks are FtS, PMs are often pushed to reduce the total duration, at which point we start planning many activities in parallel, despite the inherent risks of working based on incomplete information that may change later.
