Three Choices With One Coin

Three Choices With One Coin


  • Posted by  Downloadmela 
    10 Feb, 2012

    At a restaurant, how could you choose one out of three desserts with equal probability with the help of a coin?

    Bonus: What if the coin is biased and the bias is unknown?

    Solution
    Toss the coin twice.

    Let TH, HT and TT correspond to the three choices.

    And if you get HH, just repeat (so it takes 8/3 tosses on average).


    BIASED COIN

    If the coin was biased, TH and HT would occur with equal probabilty.

    So you could assign THHT, HTTH and THTH to the three choices, with other 4-toss outcomes rejected.

    Or you could assign HTT, THT and HTT to the three choices, with other 3-toss outcomes rejected.

2009-2016 downloadmela.com. All rights reserved.