In CPM scheduling, the critical path consists of those activities which have what value of total float?

Introduction / Context:
The critical path identifies the controlling chain of activities that determines the project duration. Float (slack) indicates permissible delay without affecting overall completion. Recognising the float characteristic of critical activities is fundamental to controlling schedule risk.

Given Data / Assumptions:

• Total float is computed from early and late times for starts and finishes.
• Critical path activities set the project finish; delaying any of them delays the project.
• Only one option correctly states the float condition for critical activities.

Concept / Approach:
Total float for an activity is TF = LST - EST = LFT - EFT. For critical activities, TF = 0. Noncritical activities may have positive TF. Negative float can arise under imposed deadlines tighter than the current plan and signals an infeasible schedule requiring compression or resequencing, but critical path is defined by zero total float in standard analysis.

Step-by-Step Solution:
Define total float and compute for path activities.Observe that critical path activities have TF equal to zero by definition.Select Zero as the correct option.

Verification / Alternative check:
Network analysis tools highlight critical activities with TF = 0 and track near-critical ones with low but positive TF.

Why Other Options Are Wrong:

• Positive: Indicates noncritical slack is available.
• Negative: Indicates schedule overrun against constraints, not the basic definition of critical path.
• Same: Vague, does not specify value.

Common Pitfalls:
Confusing negative float with criticality; assuming any low float means critical when only TF = 0 qualifies.

Final Answer:
Zero