What is Critical Path Method (CPM)?

The Critical Path Method is the analytical technique behind the critical path: a forward pass through the network calculates the earliest each activity can start and finish; a backward pass calculates the latest; the difference at each activity is its float.

You rarely hand-calculate full networks on the modern exam, but you're expected to reason with the outputs — which path drives the date, which activities have slack, and what happens when a dependency changes.