Network time computations: Which statements about forward pass, backward pass, and event time selection rules are correct in CPM/PERT?

Introduction / Context:
CPM/PERT network calculations proceed in two sweeps: a forward pass to determine earliest times and a backward pass to determine latest permissible times. Decision rules at merge and burst nodes ensure logical consistency of the schedule.

Given Data / Assumptions:

• Deterministic or expected activity durations are available.
• Events may have multiple predecessors (merge) or successors (burst).
• Zero or positive floats only (no negative float assumed here).

Concept / Approach:

Forward pass sets event TE as the greatest of the earliest finishes of all immediate predecessors, ensuring no activity starts before all its predecessors finish. Backward pass sets event TL as the least of the latest starts of all immediate successors, ensuring no successor is delayed unnecessarily.

Step-by-Step Solution:

Verification / Alternative check:

Worked examples in any CPM/PERT text produce identical results when these rules are applied consistently.

Why Other Options Are Wrong:

Each rule listed is correct; omitting any would yield inconsistent or infeasible schedules. Therefore “All of the above” is the right choice.

Common Pitfalls:

Using min instead of max in forward pass, or max instead of min in backward pass; mixing activity and event times.

Final Answer:

All of the above