The Critical Path Method (CPM)

The critical path is a concept derived from the Critical Path Method (CPM), which is a project management technique used to determine the sequence of activities that must be completed on time in order to complete a project within its scheduled duration. It helps project managers identify the most critical activities that could potentially impact the project's overall duration.

Key Purpose
The critical path helps project managers to:

- Determine the total project duration
- Identify activities that have no flexibility in their start or end dates
- Allocate resources efficiently
- Develop a realistic project schedule
- Identify potential bottlenecks or delays

Definition
The critical path is the longest sequence of activities in a project network diagram. It represents the shortest possible duration in which the project can be completed. Any delay in activities along the critical path will directly impact the project's overall duration.

Calculation
To calculate the critical path, the project manager must first create a project network diagram. This diagram visually represents the project's activities and their dependencies. Each activity is represented by a node, and the arrows between the nodes represent the dependencies between activities.

Once the network diagram is created, the project manager can calculate the earliest start time (EST) and latest finish time (LFT) for each activity. The difference between the EST and LFT for each activity is called the float or slack time. Activities with zero float time are considered critical as any delay in these activities will delay the project's completion.

Total Project Duration
The critical path determines the total project duration because it consists of the longest sequence of activities. If any activity on the critical path is delayed, it will directly impact the project's overall duration. Therefore, the project manager must carefully monitor and manage the activities on the critical path to ensure the project is completed on time.

Total Cost and Delay
The critical path does not determine the total cost or delay of a project. While it helps identify activities that could potentially cause delays, it does not provide information about the cost associated with each activity or the overall project cost. Cost estimation and project scheduling are separate processes that require different techniques and considerations.

Therefore, the correct answer is option 'A' - the critical path determines the total project duration.