# PjM Form 2 Question 37 of 75

The question states " The project schedule in the diagram above has 12 activities needed for the project’s completion. These activities are labeled A-L.
How many activities must be completed before activity G can start?"
The answer is “The answer is 4. This is an example of a network diagram. In a network diagram, activities exist in a sequence which determines when the activities can be completed based on the other activities in the project. All activities connected by a line must be completed before other activities can start. In this example, Activities A, B, C, and D must all be completed before activity G starts.
I’m confused as to why it isn’t 2, seeing as it is a clear path to G and both require 2 activities to reach G. I also tried to look up Network Diagram in the AHPP and could not locate it. I just don’t understand the logic behind this diagram. What is the point of it?

I’ll see if I can help!

A network diagram is a way to visualize all tasks which must be completed to accomplish a larger goal. In the example you’ve posted, tasks A, C, B, & D all must be completed before G can be as G is dependent on these preceding tasks.

This diagram is used to show dependencies and sequences of tasks. You might also hear this type of diagram referred to a “Critical Path Network Diagram”. These diagrams use the Critical Path Method, which you can read about more in the AHPP on page 632 & 685 if you’re interested! The critical path method is a scheduling strategy which looks at the time period associated with tasks while accounting for dependencies in order to find the optimal sequence of events and help determine float.

Here’s a free online resource I found describing network diagrams:

And here’s a very readable blog on Critical Path Method:

There’s also some good Youtube videos out there that do a deep dive into how to use these charts:

Hope this helps!
-Darion

I appreciate the resources! Thanks for the thorough response.

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