SSI chips, essential to the running of a computer system, fail in
accordance with a Poisson distribution with the rate of one chip
in about five weeks. If there are two spare chips on hand, and if
a new supply will arrive in eight weeks, what is the probability
that during the next eight weeks the system will be down for a
week or more, owing to a lack of chips?
在网络上也看到这题 但好像没有正确的答案
不知道小弟这样解对不对
将两个chip当作独立事件讨论