How Do Project Managers Identify the Critical Path in Simple Network Diagrams?

Calculating Critical Path Examples: Step-by-Step Guide for PMP Exam Prep

Learn how to identify the critical path in a project schedule using a simple network diagram example. Understand how calculating the longest sequence of dependent activities helps project managers determine the overall project duration.

Question

A project has three activities: A (3 days), B (2 days, depends on A), C (4 days, depends on A). What is the critical path?

A. A → B
B. A → C
C. B → C

Answer

B. A → C

Explanation

The critical path in a project schedule is defined as the sequence of dependent activities that results in the longest overall duration, which fundamentally determines the shortest possible completion time for the entire project. In this scenario, both activities B and C depend on the completion of activity A (which takes 3 days). This creates two possible paths through the project network: Path 1 is A followed by B (total duration: 3 days + 2 days = 5 days), and Path 2 is A followed by C (total duration: 3 days + 4 days = 7 days). Because Path A → C takes 7 days—which is longer than the 5 days required for Path A → B—it represents the critical path, as any delay in activities A or C will directly extend the project’s overall completion date beyond 7 days.