For each of the attached network diagrams, determine both the critical path and the expected project duration. The number on the arrows represent expected activity times.
It does seem like a confusing concept, but both statements are true. I couldn't get a pic of the graph off the pdf you posted, so I encourage you to look at it while I explain.
The longest path also includes steps that can overlap. This means be produced at the same time. For example. If you are working in an automotive assembly line assembling cars and your job is to install the steering wheel. Well you cannot install the steering wheel until the preceeding unit has molded the body. So Molding the body would be node A and would have to be on the critical path.
Your best friend also works with you but his job is to install the back seat. Imagine Node A breaking into 2 nodes B and C. B is your friends activity and it takes an hour to install the seat. C is your activity and lets say you install ...
Determining critical path AOA and AON