The following PMP® exam sample question is taken from http://www.free-pm-exam-questions.com – The answer is at the very bottom:

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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 duration you will put into your schedule for this activity if you want to put some weight on the expected scenario?"

A. 7 days
B. 7.5 days
C. 6 days
D. 6.5 days

Hint : Use PERT to calculate.
Reference: PMBOK4 – pg:150
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Explanation:Since you want to put some weight on the expected scenario, you will use the PERT formula. Your estimate will then be 6.5 days. Hence choice D is the correct answer.