t**********y 发帖数: 30 | 1 题目如下:
Suppose that event A occurs at intervals that are IID exponential (Alpha),
and event B occurs at intervals that are IID exponential (Beta). Here, the
parameters denote the hazard rates, the means being their reciprocals.
Suppose that a timer is started when event B occurs (call it the 0-th
occurrence of B) and it is stopped when event B occurs three more times. Let
N be the number of times event A occurs while the timer is on. Find the
distribution of N.
一遇到这种Poison问题就晕菜了,请大侠们指点,多谢! | g********5 发帖数: 62 | 2 N is negative binomial distribution.
Prob( N = k ) = (k+2 choose 2)* p^k * (1-p)^3
where p = alpha/(alpha+beta) |
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