The following PMP® exam sample question is taken from http://www.free-pm-exam-questions.com - The answer is at the very bottom:
PMBOK Section: Estimate Costs
Process Group: Planning Process Group
Question Type: Calculation
Knowledge Area: Cost Management
Difficulty Level: Easy
Question: You are managing an amusement park development project. You have received the following estimates for site excavation and area development activity that is critical to the success of your project. The most likely estimate is $100,000, the optimistic estimate is $90,000, and the pessimistic estimate is $120,000. What is the expected activity cost?
Reference: PMBOK4 - pg:173