# hw10 - Homework 10(09 April 2015 1 The time to failure of...

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Homework 10 (09 April 2015) 1. The time to failure of an electrical connector is lognormal with a shape parameter of 0.73. Since failures, measured in operating hours, were observed to be related to the operating temperature of the connector and the number of electrical contacts, the following covariate model was derived: ( ) where is the operating temperature in degrees centigrade and is the number of contacts. A particular connector used in a personal computer will operate at 80 and has 16 contact pins. What s its reliability over a 5000-hr life? 2. From the following failure times, obtained from a reliability test program, construct an exponential least-squares plot of failure data. Failure time, ( ) 3.3 4.2 12.9 13.8 14.3 14.8 18.5 22.8 27.1 29.7 32 39.5 41.3 41.6 51.1 61.7 92.2 106.6 148.8 198.1 3. The following data were collected on the number of production runs that resulted in a

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Unformatted text preview: 106.6 148.8 198.1 3. The following data were collected on the number of production runs that resulted in a failure that stopped the production line: 5, 8, 2, 10, 7, 1, 2, 5. Therefore, if the random variable of interest, X, is the number of production runs necessary to obtain a failure, 1) What’s the probability distribution for X? 2) What’s the maximum likelihood estimate for the parameter? 3) What’s the probability that the line will fail during the third run? 4. Repair times of a mechanical pump are believed to follow a lognormal distribution. Twenty-five repair times (in minutes) were observed as part of a maintainability demonstration: 47.1 84.8 151.9 122.5 218.2 99.6 59.8 138.8 213.5 53.4 102.4 100.8 230.1 104.6 61.5 122.1 186.2 498.4 77.0 78.7 112.3 44.0 151.3 151.3 222.8 Find the MLEs for the lognormal distribution....
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• Winter '14
• Normal Distribution, Failure rate, following failure times, production runs, exponential least-squares plot, reliability test program

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