A dummy activity in an AOA (activity-on-arrow) CPM network is used to:
Choose the correct answer
Represent an activity with zero cost but positive duration
Maintain logical dependency where two activities share the same start and end nodes
Identify activities that are not on the critical path
Represent activities with 100% float
Correct Answer
B. Maintain logical dependency where two activities share the same start and end nodes
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Dummy activities have zero duration and zero resources — they only show logical dependency. Used when: (1) two parallel activities share the same tail and head nodes (would create duplicate arrows), or (2) one activity's start depends on only part of a preceding set. Dummies appear as dashed arrows in AOA diagrams.
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