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Unformatted text preview: ENGRD 2700 F11 Basic Engineering Probability and Statistics Homework 3 The same conditions as outlined on Homework 1 apply to this work too. In particular, you may work with a partner and hand in a single homework with both your names (and net IDs, sections) on it. Ensure that your work is well presented, and your ideas are communicated clearly and concisely. 1. A certain service elevator serves a building by continuously moving up and down, serving the floors 1, 2, 3, 4, 5, 4, 3, 2 in that order and then repeating the cycle. It spends 30 seconds at each floor except Floor 4 where it spends 1 minute 30 seconds. Assume that the travel times between floors are negligible. You arrive at the elevator some time in the future. (a) Write down a probability model for the elevator location (floor and direction) at the moment you arrive. Be sure to specify the outcome space and probabilities for each outcome. (b) Suppose you come to the elevator on the second floor and want to go up. What is the chance that when the elevator arrives or will arrive it is indeed going up? (If the elevator is present and heading up when you arrive, then that counts as a success.) Remember that for full marks on this and all other questions you need to clearly and succinctly state your assumptions and reasoning, and probability statements must be made precisely. (c) Suppose that you come to the elevator on the 5th floor when the elevator has only just changed floors, and the elevator is not there. What is the probability that you will have to wait at most 3 minutes for the elevator?minutes for the elevator?...
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This note was uploaded on 09/30/2011 for the course ENGRD 2700 at Cornell University (Engineering School).