Question

Suppose that when a transistor of a certain type is subjected to an accelerated life test, the lifetime X (in weeks) has a gamma distribution with mean 20 weeks and standard deviation 10 weeks.

(a) What is the probability that a transistor will last between 10 and 20 weeks? (Round your answer to three decimal places.)


(b) What is the probability that a transistor will last at most 20 weeks? (Round your answer to three decimal places.)


Is the median of the lifetime distribution less than 20? Why or why not?The median is  ---Select--- equal to less than greater than 20, since

P(X ≤ ) = .5.

(c) What is the 99th percentile of the lifetime distribution? (Round your answer to the nearest whole number.)


(d) Suppose the test will actually be terminated after t weeks. What value of t is such that only 0.5% of all transistors would still be operating at termination? (Round your answer to the nearest whole number.)

t =  weeks

Answer 1