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PMP Practice: Determine Critical Information Requirements

Question 6 of 15 in Develop an Integrated Project Management Plan

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Pepper Lindström-Ali is managing a municipal water treatment facility upgrade for Elif Karahan Authority. During integrated planning, she receives three-point duration estimates from the engineering team for the critical filtration system installation activity. The optimistic estimate is 18 days, the most likely estimate is 24 days, and the pessimistic estimate is 42 days. The sponsor has asked Lila to provide a realistic expected duration for this critical path activity to finalize the project schedule baseline. The sponsor emphasized that this duration will be used for regulatory compliance reporting and contractor performance bonds, so accuracy is essential. Using the beta distribution method for three-point estimation, what expected duration should Lila report?
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Correct answer: 26 days

Explanation

Using the beta distribution formula for three-point estimation (also called PERT), the expected duration is calculated as: (Optimistic + 4 × Most Likely + Pessimistic) ÷ 6. Substituting the values: (18 + 4 × 24 + 42) ÷ 6 = (18 + 96 + 42) ÷ 6 = 156 ÷ 6 = 26 days. This weighted average formula gives more emphasis to the most likely estimate, making it more realistic than a simple average. Since this activity is on the critical path and will be used for regulatory reporting and contractor bonds, using the proper estimation technique is essential for creating an accurate schedule baseline. The beta distribution method is the standard approach in predictive project planning when dealing with uncertainty in activity durations.

**Why not A:** An expected duration of 25 days does not result from the beta distribution formula. The PERT formula (18 + 4 x 24 + 42) ÷ 6 yields 156 ÷ 6 = 26 days, not 25. This answer may reflect a simple average or a rounding error in calculation.

**Why not B:** An expected duration of 24 days simply uses the most likely estimate without applying the PERT weighted formula. The three-point estimation technique specifically accounts for optimistic and pessimistic scenarios to produce a more realistic weighted average, which is 26 days in this case.

**Why not C:** An expected duration of 28 days is too high and does not result from the correct formula. The calculation (18 + 96 + 42) ÷ 6 = 156 ÷ 6 = 26 days. An answer of 28 might result from an arithmetic error or using an incorrect weighting approach.

Key Concept

This question covers Determine Critical Information Requirements under Develop an Integrated Project Management Plan (Process).

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