***Critical Path - Question***

 You are the project manager for Software Development project. The feasibility study can start any time and takes 1 week and Requirement gathering takes 2 weeks which can start only after feasibility study. The Design and Test Plan development can start in parallel after the Requirements gathering.Test plan preparation takes 8 weeks followed by a review by the customer and the time estimated for review is 1 week. After the review, Test Data preparation takes 6 weeks. Design takes 6 weeks and it is followed by Development and Unit Testing, for one module it takes 2 weeks and for the other module it takes 2 weeks. There are no dependencies between modules and they can be developed simultaneously. After Test Data preparation and Development and Unit testing of both the modules, there is 2 weeks system testing.

What is the lag time on the critical path?


1 week

2 weeks

3 weeks


Correct Answer - 1 Week 

My Answer - 0 week 

As per my understanding, there should not be any Lag time on the Critical Path based on above scenerio as none of the activities is waiting for specific time after the predecessor activity is completed. 

Please advise.

Regards, Sam






 From where did u get this question?

 one of the site...might be PM Track 

 As per my understanding there can be zero float or -ve float in Critical path. So the answer should be Zero Lag

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The correct answer must be Zero, you are right. That is why I asked you from where did u get this? Again, i have to say, beware of this kind of reference that will cause your failure, or at least take its possitive impact on you as you learn more, the more you discover error he he he! Then, find more erroneous Q&A then. 

I made a detailed analysis and answer to this question in my thread with graph, since i cannot paste or attached it here, please follow this link. http://www.pmptrend.com/index.php/en/forum/11-Questions-Answers-Queries-Infos-Etc/48-What-a-wrong-PMP-sample-QA#48

Very nice and clear explanation...I am in full agreement with your explanation.

Thanks for the effort Projmanpro !! 



Thanks a lot Sam, you can follow my threads in that website www.pmptrend.com too..  i am online there if i am offline here in pmzilla.

Dear Friends,


Actually there would be no answer.

Because this question is wrong.

On critical path or any one path Lag or Lead not happened.

On critical path even no float is possible.

Lag or Lead is a relative term in between two tasks or activities.

I will go in detail if require later.



The question is just a tricky question dear. It is correct. BUT the choice of the author or the website from which that question was taken was wrong.

In my post above, i emphasized that lag or lead could be in a critical path if so required or said in the questions's conditions. However, since lag or lead was never implied in the question's condition, the correct answer must be Zero.

As regards whether or not lag or lead could be in a critical path, see this thread i attached a graph to visualize.


Dear frnd

Yes q is tricky and answer will be zero.

I have also seen that gantt chart .

As the question asked :

what is the lag time on critical path.

Does not require to scrutnize the whole question.

Because it is universal truth that critical path or any single path does not have any lag time.

Lesson learned  here is:

if question is lengthy/ wordy/ unclear then  - read it from end. It is possible that only last line will solely decide your answer.

Do you feel that this long calculation is required in PMP pattern question.

It is time killing question , hence use the trick - read from last line if question is wordy.



agree with u, since the question is long and worthy, the recommended strategy is to jump directly to the main question and analyze from there. that's my point of emphasis in my thread. thanks for contributing dude. You can write also to pmptrend forum if u want.

 " Because it is universal truth that critical path or any single path does not have any lag time."  By SSPawar

My Comment :

Critical Path can have Lag  but not Float.... ( Correct me if  I am wrong)




sam, you are correct, this is what i am emphasizing. SSPawar was wrong to say that critical path has no lag. Critical path can have a lag or lead, but in no case has a float. the gantt chart i iprepared in my pmptrend.com post clearly shows this fact - that a lag or lead can be in the critical path.

Hi frnds


Realy interesting----

I mean to say any one complete path versus an another complete path, can not be associated with lag or lead.

Let us read question once more:

What is the lag time on the critical path?

Lag or lead is a relative term, which always exists among 2 activities.

I mean activity /task versus another activity /task, and it never be path versus path.

In CPM and PERT , methods lag or lead are only  activity asociated terms.

Whenever anybody will talk about lag or lead, he /she has to compare 2 objects. it is relative term.

it is not a independent term.

for example speed or mass are independent terms or properties where any Index like Humidity or Relative density are relative properties.

or like two trains ar running side by side on 2 tracks, here lag will be relatively from one early left train to another delayed train. some one can ask what is lag time of delayed train with respect to fearly train, rather asking what is lag time on this track (bet station A to station B).

So as per question for Lag or lead you have to be compare with another path. it seems some incorrect questioning.


In other way it is true that acivities belong to a path and hence lag will also be associated with path.

I agree with you in this contest that any path can have lag or Lead , whether it is critical or not critical, and path can have number of lag/lead incidences as described in below thread.

A video preaentation of lag and lead in MS Pro, here is a thread -


One more thing, Lag or Lead is not a type of Float.



Good Explanation.

Lag n lead does not constitute a Float



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