条件概率的问题设苹果树上开N朵花是随机事件,且服从概率分布函数P[N=n]=(1-p)p^n,p属于(0,1)区间,又假
条件概率的问题
设苹果树上开N朵花是随机事件,且服从概率分布函数P[N=n]=(1-p)p^n,p属于(0,1)区间,又假设每朵花结果的概率的是a,且各朵花之间结苹果是独立的.
现在树上有r个苹果,请问树上原先有n朵花的概率是多少?
回复nowusing:
我开始的思路基本和你一样,在你的这一步中“P(R=r) = C(N',r)(1-ap)^(N'-r)(ap)^r”,
你是假设N‘是已知的,所以依照你的思路可以解题,但是这是未知的。还有,开花的概率你理解的有一点问题
我再给你描述下英文的原题吧:
The number of flowers N appearing on an apple tree is a random variable,with distribution P[N=n]=(1-p)p^n,for some p属于(0,1).Assume that a flower turns into a fruit with probability a independently from the other flowers on the tree.
Given that tree there is a number r of apples on the tree,what is the probability that originally there were n flowers on it?