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Unformatted text preview: EE 178 Handout #2 Probabilistic Systems Analysis January 17, 2008 Homework #2 Due Thursday, January 24, 2008 1. Catching the train. The probability that Riddley Walker goes for a run in the morning before work is 2 / 5. If he runs then the probability that he catches the train to work is 2 / 5. If he does not run then the probability that he catches the train to work is 1 / 2. If he does not catch the train, then he catches the bus. The model holds Monday through Friday. a. Draw a tree showing the probabilities governing Riddleys morning. b. What is the probability that Riddley catches the train any morning? c. You are told that Riddley made the train what is the probability that he ran? 2. Testing for a disease. The probability that a man has a particular disease is 1 / 20. John is tested for the disease but the test is not totally accurate. The probability that a person with the disease tests negative is 1 / 50 while the probability that a person who does not have the disease tests positive is 1 / 10. Johns test returns positive. a. Find the probability that John has the disease. b. You are now told that this disease is hereditary. The probability that a son suffers from the disease if his father does is 4 / 5, the probability that a son is infected with the disease even though his father is not is 1 / 95. What is the probability that Steve95....
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- Spring '08