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Probability of missing items

  1. Jul 22, 2014 #1
    1. The problem statement, all variables and given/known data

    i have problem of finding P(C) , why cant i use the method as in the photo to find P(C) beacuse 1-(all unused stamps are missing)= at least 1 use stamps is missing.

    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Jul 22, 2014 #2

    Simon Bridge

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    C is the event at least one of the used stamps is missing.

    "all unused stamps are missing" would mean there are 14 stamps missing - but the problem statement says only three are missing.

    Did you mean, "all missing stamps are "unused"" - but that is not correct either since at least one of them has to be "used".

    even C is the same as "at most two of the missing stamps are unused"

    You need to comment your working.
     
  4. Jul 22, 2014 #3
    Ya I mean all the 3 stamps missing are unused.
     
  5. Jul 22, 2014 #4

    Simon Bridge

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    So if you write: D:=event all three missing stamps are unused, then you want to argue that P(C)=1-P(D), is that what you are saying?
     
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