PMP Process — Managing Technical Aspects Practice Question
You are managing a project to develop a new mobile application. The project is in the planning phase. You are working with your team to estimate the duration of each activity. For a particular activity, 'Develop user login module', the team has provided the following estimates: Optimistic (O) = 5 days, Most Likely (M) = 8 days, Pessimistic (P) = 17 days. Using the PERT (Program Evaluation and Review Technique) formula, what is the expected duration for this activity?
⚠ Common exam trap
The trap here is using the simple average (O+M+P)/3 instead of the PERT weighted average.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
9 days
The PERT formula for expected duration is (O + 4M + P) / 6. With O=5, M=8, and P=17, the calculation yields (5 + 32 + 17) / 6 = 54 / 6 = 9 days. This weighted average is used to account for uncertainty and is a standard technique in activity duration estimating.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
9 days
Why this is correct
The PERT expected duration is calculated as (O + 4M + P) / 6. Plugging in the values: (5 + 4*8 + 17) / 6 = (5 + 32 + 17) / 6 = 54 / 6 = 9 days. This weighted average gives more weight to the most likely estimate and is used to account for uncertainty in activity duration estimates.
- ✗
8 days
Why it's wrong here
This is the most likely estimate (M), but PERT weights the optimistic and pessimistic estimates to account for uncertainty. Using only the most likely estimate ignores the risk and variability inherent in the activity. The PERT formula provides a weighted average that is more realistic for project scheduling.
- ✗
10 days
Why it's wrong here
This is the simple average of the three estimates: (5 + 8 + 17) / 3 = 10 days. However, PERT uses a weighted average that gives four times the weight to the most likely estimate. The simple average does not reflect the beta distribution that PERT assumes, making it less accurate for project duration estimation.
- ✗
12 days
Why it's wrong here
This value does not correspond to any standard estimation formula for these numbers. It might result from a miscalculation or using a different weighting. The PERT formula is specific and yields 9 days. Using an incorrect duration could lead to inaccurate schedule development and potential delays.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official PMI exam blueprint
This PMP practice question is part of Courseiva's free PMI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PMP exam.