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**wopashui** Suppose that a critical component of an experiment to be performed on a space shuttle has an expected lifetime of 10 days which is exponentially distributed. As soon as a component fails, an identical component instantaneously takes its place. If the mission lasts 10 days and there are 2 spare components on board, what is the probability that these 3 components last long enough for the space shuttle to accomplish its mission?

Answer this question (i) using an appropriate continuous distribution, and (ii) using an appropriate discretedistribution.

for (i), I have use the exp(30) distribution to find the probability is 0.7165, but im kind of stuck with the diecrete one, i know it should be possion, but what is lamda, is it1/30?