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Suppose you are given a biased coin for which the probability of getting a head is $p (0<p<1)$.Discuss how you will select one of two individuals at random using the biased coin.

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Flip the coin. That's it. The choice will still be random, but it will be biased. If you want to try to make the choice .5 for each person, then see the link @Procrastinator gave. –  Peter Flom Nov 24 '12 at 16:31
A technique for making an unbiased selection using biased coin goes back to Von Neumann‌​. –  whuber Nov 24 '12 at 16:39
There are plenty of ways other than Von Neumann's. (One amusing method: buy something cheap with the coin and flip one of the coins you get for change.) A good answer to this question might describe more than one way and assess their properties, such as the bias (if the solution only approximates a fair coin) and the expected number of flips needed to make a selection. –  whuber Nov 24 '12 at 17:00
One nice thing about the Von Neumann solution is that it does not require us to know how biased the coin is... –  Stephan Kolassa Nov 24 '12 at 19:45
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