easyMultiple Choice
PK0-005 Practice Question: A project manager is estimating the duration of a…
A project manager is estimating the duration of a task that has never been done before. The team provides three estimates: optimistic (4 days), most likely (7 days), and pessimistic (16 days). Using the PERT three-point estimate formula, what is the expected duration?
⚠ Common exam trap
CompTIA often tests the PERT formula by including a distractor that is the simple arithmetic mean (9 days), tempting candidates who forget the weighted 4× multiplier for the most likely estimate.
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
✓
8 days
The PERT three-point estimate formula is (Optimistic + 4×Most Likely + Pessimistic) / 6. Plugging in the values: (4 + 4×7 + 16) / 6 = (4 + 28 + 16) / 6 = 48 / 6 = 8 days. This weighted average accounts for uncertainty in tasks with no historical data, giving more weight to the most likely estimate.
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 it's wrong here
PERT weights the most likely estimate fourfold: (4 + 4×7 + 16) ÷ 6 = 8 days, not 9. Nine is the triangular-distribution average, (4+7+16)÷3, which treats all three estimates as equally likely. PERT is the right technique for this novel task; the triangular mean applies when no estimate is more probable than the others.
- ✓
8 days
Why this is correct
PERT weights the most likely estimate fourfold: (4 + 4×7 + 16) ÷ 6 = 48 ÷ 6 = 8 days. This satisfies the stem's requirement to apply the three-point formula to a novel task, yielding the expected duration rather than the simple average of 9 days.
- ✗
7 days
Why it's wrong here
Seven days is merely the most likely estimate, ignoring the optimistic and pessimistic values entirely. PERT requires all three inputs, weighted fourfold on the most likely: (4 + 4×7 + 16) ÷ 6 = 8 days. The most likely figure alone would be used only for a simple, well-understood task with negligible uncertainty.
- ✗
10 days
Why it's wrong here
PERT weights the most likely estimate fourfold: (4 + 4×7 + 16) ÷ 6 = 8 days, not 10. The figure 10 is simply the arithmetic mean of the three values, which ignores the weighting. PERT suits novel, uncertain tasks exactly like this one; the plain average would apply only if all three estimates carried equal probability.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PK0-005 practice question is part of Courseiva's free CompTIA 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 PK0-005 exam.