An actuary determines that the numbers of major earthquake in certain area follows Poisson distribution with mean 2 per year. 1. whart is the probability that the inter-arrival time of two major earthquakes is less than three months? 2. what is the probability that there will be no major earthquakes in a year? 3. counting the number of no major earthquake years in the next 10 years, what is the probability that the count is two. 4. counting the number of no major earthquake years in the next 100 years, what is the probability that the count is over 15. 题目如上述，是否可请各位大大帮忙解题，小弟一直苦无头绪，也不知如何下笔。 看起来是卜瓦松过程，但还是不知要如何解题，也不太清楚题意，是否可以请各位 赐教，谢谢!! -- --

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