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The blade and the bearings are important parts of a lathe.
Chapter 5, Problem 22E(choose chapter or problem)
The blade and the bearings are important parts of a lathe. The lathe can operate only when both of them work properly. The lifetime of the blade is exponentially distributed with the mean three years; the lifetime of the bearings is also exponentially distributed with the mean four years. Assume that each lifetime is independent.
(a) What is the probability that the lathe will operate for at least five years?
(b) The lifetime of the lathe exceeds what time with 95% probability?
Questions & Answers
QUESTION:
The blade and the bearings are important parts of a lathe. The lathe can operate only when both of them work properly. The lifetime of the blade is exponentially distributed with the mean three years; the lifetime of the bearings is also exponentially distributed with the mean four years. Assume that each lifetime is independent.
(a) What is the probability that the lathe will operate for at least five years?
(b) The lifetime of the lathe exceeds what time with 95% probability?
ANSWER:Solution
Step 1 of 3
Let be the lifetime of the blade
And it is exponentially distributed with mean 3 years
Let be the lifetime of the bearings
And it is exponentially distributed with mean 4 years
The pmf of exponential distribution is
Then
And