In CPM/PERT, zero slack on a task implies what?

In CPM/PERT, zero slack on a task implies what?

• A. Zero slack means the task is on the critical path
• B. Zero slack means the task can be delayed without affecting the project duration
• C. Zero slack means there is negative duration
• D. Zero slack means the task has free float

Answer: (A)

Slack in CPM/PERT measures how much a task can be delayed without pushing the overall project finish date. When a task has zero total slack, there is no room to delay it without extending the project's duration. That’s why such tasks form the critical path—the sequence of activities that determines the project’s completion time. So zero slack implies the task is on the critical path because any delay shifts the finish date. In contrast, the idea that the task can be delayed without affecting the project duration is incorrect, since zero total slack means there is no allowable delay. Negative slack is not a normal state for a scheduled task (it indicates the project is already behind). Free float refers to delay possible without affecting a specific successor, which is a different measure from total slack.

Slack in CPM/PERT measures how much a task can be delayed without pushing the overall project finish date. When a task has zero total slack, there is no room to delay it without extending the project's duration. That’s why such tasks form the critical path—the sequence of activities that determines the project’s completion time. So zero slack implies the task is on the critical path because any delay shifts the finish date.

In contrast, the idea that the task can be delayed without affecting the project duration is incorrect, since zero total slack means there is no allowable delay. Negative slack is not a normal state for a scheduled task (it indicates the project is already behind). Free float refers to delay possible without affecting a specific successor, which is a different measure from total slack.