ISEB ISEB-PM1 Exam Draw the precedence diagram for the dependencies and activity times below to answer the question. Use AON or another technique to derive the answer using F-S relationships. What…

Question

Options

• A0
• B1
• C2
• D3

• A
  3% (1)
• B
  7% (2)
• C
  73% (22)
• D
  17% (5)

Explanation

Option C (2) is correct because total float measures how much a path can be delayed without pushing back the project end date, calculated as project duration minus path duration (or Latest Finish – Earliest Finish for the path's last activity). For path BEG, the sum of activity durations falls 2 time units short of the critical path length, giving it exactly 2 units of float.

Option A (0) is wrong because zero float would mean BEG is on the critical path - any delay would directly delay the project, which is not the case here. Option B (1) underestimates by one unit, likely resulting from a forward-pass or backward-pass arithmetic error in the network diagram. Option D (3) overestimates by one unit, a common mistake when confusing total float with free float or misreading the latest finish date from the backward pass.

Memory tip: Think of total float as "slack before panic" - it's the buffer a path has before it becomes critical. Always verify it on both the forward pass (earliest dates) and backward pass (latest dates): Total Float = LS − ES = LF − EF. If any activity on the path has 0 float, the whole path is critical.

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