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Suppose that the probability that a head appears when a coin is tossed is p and the probability that a tail occurs is q=1-p. Person A tosses the coin until the first head appears and stops. Person B does likewise. The results obtained by persons A and B are assumed to be independent. What is the probability that A and B stop on exactly the same number toss?

I am not quite sure how to solve this. I'm assuming that the tosses are distributed as a negative binomial and I'm lost as to how to put everything together.Please help !

Thanks!

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# Joint Coin Probability Problem

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