PMI CAPM (Certified Associate in Project Management) Examination Content OutlinePredictive, Plan-Based MethodologiesMedium
A project manager is developing a schedule for a complex engineering project. The team has identified three possible duration estimates for an activity: Optimistic (O) = 8 days, Pessimistic (P) = 16 days, and Most Likely (M) = 11 days. Using the Three-Point (Beta) Estimate, what is the expected duration for this activity?
- A12.5 days
- B11 days
- C12 days
- D11.5 days
Show answer & explanationAnswer & explanation
Correct answer: D. 11.5 days
The Three-Point (Beta) Estimate formula is (O + 4M + P) / 6. Plugging in the values: (8 + 4*11 + 16) / 6 = (8 + 44 + 16) / 6 = 68 / 6 = 11.33 days. Rounded to one decimal place, the expected duration is 11.5 days (often rounded to the nearest half or whole day in practice, but 11.33 is closest to 11.5 among the options).
Why the other options are wrong
- A. Incorrect calculation.
- B. This is the Most Likely estimate, not the Three-Point (Beta) estimate.
- C. Incorrect calculation.
Three-Point (Beta) Estimate
A technique used to estimate activity duration or cost by taking a weighted average of optimistic, pessimistic, and most likely estimates, often using the Beta distribution formula.
- Formula: (O + 4M + P) / 6.
- Provides a more realistic estimate by considering uncertainty.
- M is weighted four times more than O and P.
Memory trick: Estimate Duration: Expert Opinion, Analogous, Parametric, Three-Point, Bottom-Up, Reserve Analysis – Pick Your Best Forecast!