CEE_597_Final2001r

CEE_597_Final2001r - CEE 597 Risk Analysis and Management...

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Page 1 of 4 CEE 597 – Risk Analysis and Management Final Exam Thursday --- May 17, 2001r --- noon to 2:30 pm. Test is open book and open notes. You have 150 minutes for this 150 point exam. Write clearly and show important steps. And remember, I hope you learned more than I could include on this exam. - JRS 1. (10 pts.) Of all the case studies/accidents in Fleddermann (DC-10, Valujet, KC Walkway, Ford Pinto, and Teton Dam ), which one did you think had the most important lesson? What key important lessons did it teach about the character of system failures? (2-3 paragraphs) 2. (10 pts.) One significant cause of death in the US is accidents. Consider how this death risk changed over the last 100 years: the rate per 100,000 was 72 deaths in 1900; 48 in 1980 and 34.6 in 1994. Given the advance of technology, speed of life, aging of the population, and investments in safety, does this trend make sense? Explain why this metric is or is not an appropriate expression of this source of life loss. Suggest another metric that you think would provide a different insight into this issue. If people live longer now, should they not have more accidents? 3. (20 pts. altogether) Consider the fault tree below. a) (4 pts.) If every component is 99.9% reliable, what is reliability of the system? b) (4 pts.) Draw a network diagram for this system. System Failure E F A B C D Consider the system described by the network below. c) (6 pts.) What are all the minimal cut sets? d) (4 pts ) If all elements are 99.9% reliable, approximately what is the RELIABILITY of entire system? e) (2 pts.) If you could upgrade ANY ONE component in the original network to a reliability of 99.99%, which would most improve the reliability of the system? B F G H D A C E
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Page 2 of 4 4. (15 pts.) Spring is the time for things to break around the house: fans, gutters, garden hoses, sump pumps, lawn mowers, fences, windows, locks, … The Stedinger family is overwhelmed. It seems there is another failure every 4 days. a) (3 pts.) At that rate, what is the probability they go a whole week without something breaking? b) (4 pts.) What are the mean and variance of the time until the next 5 failures occur? (specify units) c) (4 pts.) What is the probability of three or more failures in a single week? d) (4 pts.) If the estimate of the failure rate of one failure every four days was based upon experiencing 15 failures over 2 months, how accurate is this estimate of the true failure rate? (units) 5. (12 pts) Late one evening a special light over Prof. Stedinger’s workbench burned out and he resolved stubbornly to replace it immediately so he could finish his project. Assume there is a 30% chance the house has a spare light bulb in the spare-bulb box. If there is no spare, then there is a 20% chance that Stedinger can find a light bulb being used somewhere else in the house (and can borrow it for the workbench) that is not burnt out already. If after completing a search of the house Stedinger cannot find a bulb, he will get in his car
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CEE_597_Final2001r - CEE 597 Risk Analysis and Management...

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