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Very simple probability question

  1. Jan 3, 2013 #1
    This question has been bothering me for a while. If you roll a 6 sided die 6 times, is there a 1 probability that you with roll the number 1? What is the percent chance that you will roll the number 1? It clearly isn't 100%...
     
  2. jcsd
  3. Jan 3, 2013 #2

    Simon Bridge

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    No. You correctly intuit that there is a chance of not rolling any "1"'s at all.
    The probability of rolling a "1" is 1/6 for the die. Therefore the probability of rolling any other number is 5/6 ... since the rolls are independent, the probability of rolling anything but a 1 all six times is (5/6)^6 ... so the probability of getting at least one "1" in six rolls is 1-(5/6)^6.

    That's the shortcut - you can also set it up as a binomial probability problem.
     
  4. Jan 4, 2013 #3
    Thanks a lot!
     
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