Forward / backward pass question

tpopejr's picture

Greetings all.

I'm an old IT guy here.  I'm studying very hard but also very new to the PM world. 

In my studies, I came across a question that is confusing me.

The question asks "What is the late start of Task E?"  Their answer is week 22 but I believe it to be week 21.  From my understanding, Task E is on the Critical Path and cannot be delayed.

The attached Excel spreadsheet have, what I believe, are the correct calculations.  The JPG is the actual question with their answer explanation.  They're adding a day which would push the schedule out a day.

I would appreciate any assistance in helping me understand how my caluclations are incorrect.


Office spreadsheet icon My calculations51 KB
Image icon The actual question146.24 KB


I have come across such questions before. Basically there are 2 methods to calculate float and critical path. One where you start with 0 for the first tasks (the way you have calculated). Other method is you start with a 1.

Most of these questions assume to use 1 as starting day.

I am not sure how to answer such questions as in your example both 21 and 22 are given as options. I only hope these kind of questions dont come up in exam.

Sorry, don't have a solution.