Free PMP Exam Sample Question

The following PMP® exam sample question is taken from - The answer is at the bottom:

PMBOK Section: Estimate Activity Durations
Process Group: Planning Process Group
Question Type: Calculation
Knowledge Area: Time Management
Difficulty Level: Moderate

Question: "You are managing a construction project. You are currently estimating the duration of a very critical activity. You have gathered the following information from the experts:
Best case scenario: Activity can take 3 days to complete.
Worst case scenario: Activity may take up to 12 days to complete.
Expected scenario: On average it takes up to 6 days to complete such activities.

What will be standard deviation of the activity?"
A. 1.25 days
B. 1.5 days
C. 1 day
D. Cannot be determined by the data given.

Hint : Use PERT to find the standard deviation.
Reference: PMP Study Guide 5ed - Sybex - pg:170

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Until next time,
Cornelius Fichtner, PMP
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Explanation: Standard deviation formula for PERT (triangular distribution) is (Pessimistic-Optimistic)/6. The standard deviation of the given data, according to this formula, is 1.5 days. Hence choice B is the correct answer.