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 Post subject: ballot problem
PostPosted: Thu, 18 Mar 2004 02:19:03 UTC 
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Joined: Thu, 18 Mar 2004 01:02:25 UTC
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Hi,
Can you help me with the problems below.

1. In an election , candidate A receives n votes and candidate B receives m votes, where n>m. Assuming that all of the ((n+m)!) / n!*m! orderings of votes are equally likely. Let Pn,m denote the probability that A is always ahead in the counting of the votes.
1. Compute P2,1 , P3,2 , P5,4 , Pn,2

2. In a certain species of rats, black dominates over brown. Suppose that a black rat with two black parents has a brown sibling.
a) What is the probaility that this rat is a pure black rat (as opposed to being hybrid with one black and one brown gene)

b) Suppose that when the black rat is mated with a brown rat, all five of their offspring are black. Now what is the probability that the rat is a pure black rat.
thank you in anticipation


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PostPosted: Thu, 18 Mar 2004 09:35:36 UTC 
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Joined: Thu, 11 Sep 2003 22:17:18 UTC
Posts: 41
ok, now i know you're using the book by ross.

these are very challenging problems. i suggest reading chapter 3 of his book. it's pretty much conditional probability


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