CPM time definitions: Earliest finish time (EF) of an activity equals which time relationship?

Introduction / Context:
Forward and backward passes in CPM compute start/finish times to identify project duration and floats. Correct formulas are key to accurate networks.

Given Data / Assumptions:

• Each activity has a deterministic duration, d.
• Earliest start (ES) is known from predecessors.
• Finish times consider end-of-activity events.

Concept / Approach:
The forward pass determines the earliest times. For any activity, the earliest time it can finish is simply its earliest start plus its own duration: EF = ES + d. Backward pass analogously uses latest finish and duration to compute latest start: LS = LF - d.

Step-by-Step Solution:

Verification / Alternative check:
Test with d = 5, ES = 3: EF = 8. Any other relation gives a wrong value, confirming option (a).

Why Other Options Are Wrong:
Subtracting duration from ES or adding duration to LF mixes forward and backward pass logic.

Common Pitfalls:
Ignoring calendar constraints; misinterpreting start-to-start or finish-to-finish relationships that modify simple ES/EF logic.

Final Answer:
Earliest start time + duration of activity