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Conditional Probability Brainteaser

Tuesday 4 February 2014

You have two coins in your pocket.  One of them is double-headed and the other is a fair coin (head-tail).  You randomly choose one of the coins from your pocket.  You look at one side of it.  Given that you see 'heads', what is the probability that you've chosen the fair coin?

Tags: probability, conditional probability, puzzle, paradox, tree diagram

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