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Probability equation question

  • 18-04-2012 12:58PM
    #1
    SeaSide
    Closed Accounts Posts: 762 ✭✭✭


    Trying to figure this out and not happy with the answer I'm getting;

    I have a 10% chance of losing my mobile each year so over three years I would have a 3*1/10=30% chance of losing it. Right?

    So if I have six people including myself in my social circle what is the probability of losing one or more phones over three years.
    6*(3*1/10)=18/10 cant be right so what is the answer and what does the equation look like.

    Cheers


Comments

  • #2
    MathsManiac
    Registered Users, Registered Users 2 Posts: 1,595 ✭✭✭MathsManiac


    It's better to think of this in terms of the probability that you DON'T lose your phone.

    The probability that you don't lose your phone over the next three years is (0.9)(0.9)(0.9) = 0.729.

    So the probability that you DO lose your phone (at least once) in the next three years is 1 - 0.729 = 0.211.

    The probability that none of you loses a phone over the next three years (assuming everyon'e probability is the same as yours and independent of each other) is (0.729)^6.

    So the probability that at least one phone gets lost is 1 - (0.729)^6, which is about 0.85.


  • #3
    SeaSide
    Closed Accounts Posts: 762 ✭✭✭SeaSide


    Thanks that makes much more sense


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