I’d like to make a fair and random choice among 3 alternatives, but the only randomizing device I have available is a coin to toss. Worse yet, I suspect the coin may be biased. What to do?
A fair 3-way choice using coin tosses
One response to “A fair 3-way choice using coin tosses”
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Another method is to first flip the coin twice. If it’s HH, you have a 1 and are finished. If it’s TT, you have a 3 and are finished. If it’s HT, you still have a choice between 1 and 2. If it’s TH, you still have a choice between 2 and 3. Keep flipping the coin until you get 2 consecutive Heads or Tails. Then HT…. HH is 1, HT….TT is 2, TH…. HH is 2, TH….TT is 3. You should rarely have to flip the coin as many as 30 times, especially if the coin is biased.
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The Random Texan 
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