Activity 'C' follows activity 'A' and activity 'D' follows activities 'A' and 'B'. The correct network for the project is
- A.
- B
Correct - C
- D
Solution
Concept
Activity Precedence and Network Logic
Formula
No
Step-by-step solution
1. Identify the dependencies given in the problem: - Activity C requires Activity A to finish first. - Activity D requires both Activity A and Activity B to finish first. 2. Check the network diagrams to find the one where: - An arrow connects the end of A to the start of C. - Arrows connect the ends of both A and B to the start of D. 3. Select Option B, which correctly represents these precedence relationships.
Explanation
Option B correctly shows that activity C starts after activity A finishes, while activity D starts only after both activities A and B are completed.
Shortcut
Identify the multi-dependency activity first: 'D' needs both 'A' and 'B', so look for the node where arrows from 'A' and 'B' meet before 'D' starts. 'C' only needs 'A', so 'C' branches out directly from 'A' alone. Matching this key convergence point quickly eliminates wrong options.
Common mistake
A common mistake is failing to use a dummy activity correctly when an activity (like C) depends on only one precedent (A) while another activity (D) depends on multiple precedents (A and B), leading students to incorrectly make C depend on both A and B as well.
Correct answer: B)