Puzzle #160 Solution: Oops!

Spoiler Inside: Solution to Puzzle SelectShow

2 thoughts on “Puzzle #160 Solution: Oops!

  1. Lynne Mugford

    Could this be another oops? Shouldn’t the percentage be greater than 10 %? Since the probability of making an error is 1 %, the probability of making exactly one error in ten weeks should be 10 %?

    Thanks,

    Lynne

    1. Gene Wirchenko Post author

      Nope. Would the probability of making exactly one error in 100 weeks be 100%? Would the probability of making exactly one error in 200 weeks be 200%? The probabilities do not add in this case. Look up the birthday problem: how many people (selected randomly) are needed to have at least 50% probability that at least two of them will share birthdays? The answer is lower than you almost certainly think (if you have not seen this problem before).

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