A student of ours who was answering questions in our PMP Exam Simulator (www.pm-exam-simulator.com) recently asked for an explanation of the following question he came across:
What is the Critical Path?
A) Maximum project duration
B) Minimum project duration
C) Total slack
D) Total float
He immediately realized that answers C and D are completely wrong and did not consider them. But then he fell into the “trap” that this question was setting up and selected “A) Maximum project duration” as the correct answer. But the correct answer is in fact “B) Minimum project duration”. Let me explain why.
First let’s acknowledge that the question is intentionally worded and phrased in this way. It's not meant to mislead, it's meant to make you think about what the critical path truly is.
That much said, you will probably remember from your studies that the critical path is the longest duration that you currently have in your schedule network diagram. But this does NOT mean that the critical path is the maximum duration that your project will/could have.
Let's look at an example and let’s say that our network diagram currently says that our critical is 30 days long. Is that the maximum that our project will take? No... it's the MINIMUM.
The critical path says that if everything goes as planned and we have zero delays, then we will be done in 30 days. But if there is just one task on the critical path that gets delayed by 2 days, then our critical path (and project duration) will increase to 32 days.
Therefore the critical path is not the MAXIMUM duration that we can expect on our project. It's the MINIMUM. (But only if all goes well).