Oliver Lehmann question

Pls help me with this question.I do not understand FF  relationship between act 2 and act  3 and FS+3 relationship between act 3 and 4 .Can anyone help solving it?

Answer should be 37 days.

Calculation -

Act 1 + Act 2 + Lag of 1 day + Act 4 == 20+10+1+6 = 37

Activity 3 will finish two days before activity 2 finishes and activity 4 will start 3 days after activity 3 finishes.

so there will be one day lag between activity 2 and 4. activity 3 duration will be parallel to activity 2 so no need to add duration of activity 3.


Hi Pankaj,

please check my doubt below in Mrcurie's reply .Any input?

Act 1 starts on Day 1 and ends on Day 20

Act 2 starts on Day 21 and ends on Day 30

Act 3 can end only 2 days before Act 2  is completed, that is Day 28 ( forget when it can start)

Act 4 can start only on 28 + 3 , that is Day 31

Act 4 takes 6 days to complete, that is 31 + 6 , Day 37

I remember taking a long time to figure out what this means, when answering O Lehman questions. But finally was able to figure it out.. I have never seen this kind of question in any other mocktest, neither for the real exam.


HI Marcurie.

I did not understand when  you said

Act 3 can end only 2 days before Act 2  is completed, that is Day 28 ( forget when it can start).

FF relation ship is Act 2 should be finished before I finish Act 3.I finished Act 2 at 30th day.Here am not sure when  am starting Act 3 so why am assuming it should be finished by 30th day and applying lead 2 days to get 28 days.Please explain.This FF relationship confusing me.Because I have all liberty to choose when to finish Act3 as only dependency is Act 2 should be finished before this activity finishes.

Thanks in advance.

FF-2 between activity 2 & activity 3 means,

Activity 3 can finish 2 days before Activity 2 finishes. Hence Activity 3 will finish on day 28. Since the relationship is FF, you need not worry about the start day of activity 3.

Hope this helps.




Thanks Arun,

But again am confused wth this question.Pls check


why the duration is not 13 ?

cna you pls explain?


As far as I know, the answer should be 13 days as the relationship given is FF+3.

Activity A will finish on day 10 and since there is a lag of 3 days for Activity B to finish, the total duration should be 13 days.

The explanation given by Chandra on that forum topic speaks about a Start to Start relationship with 3 days lag whereas the question talks about FF+3.

But if anybody has an explanation for answer as 12 days, it is much appreciated.

I have mentioned the question for easy reference.

activity A has a finish - to-finish relationship with activity B. Activity A has a duration of 10 days. activity B has a duration of 9 days with a 3 day lag. what is the total duration of activty a and B?

1.7 days
2.8 days
3.12 days
4. 9 days




 Act-3 will finish on 28 days which is good. But Act-2 will finish only in 30 days. So it s after 30 days that both Act-2 and Act-3 will be done.

So I add 30 + 3 + 6 =39

Plaese explain what's wrong in this.

Dear Amar,

The 3 days of lag time should be considered between activity 3 & 4. In your calculation, you have applied 3 days from that day activity 2 finishes, but the 3 day lag starts after activity 3 finishes. So,

20(activity 1) + 10(activity 2) + 1(since 3 days lag starts on day 28 (when activity 3 finishes) and ends on day 31) + 6(activity 4) = 37 days.

Please let me know if you are still confused.




Answer would be 37 - look at leads (https://www.pmbypm.com/lead-lag/) & lags (https://www.pmbypm.com/faq-lead-and-lag/). Also check this to understand how much score is good in Lehmann tests - https://www.pmbypm.com/oliver-lehmann-pmp-questions/