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Probability Question

  • 26-10-2016 03:01PM
    #1
    timmy_mallet
    Closed Accounts Posts: 1,165 ✭✭✭


    My Grandmother has 6 Great Grand Children - all boys.
    Her next Great Grand Child to be born - what is the probability it will be a girl?


Comments

  • #2
    learn_more
    Closed Accounts Posts: 1,520 ✭✭✭learn_more


    Do we take into account the probability that one of them might be homosexual?


  • #3
    Peregrinus
    Registered Users, Registered Users 2, Paid Member Posts: 28,026 ✭✭✭✭Peregrinus


    This is not really a maths question. If the propensity to bear male children is a genetically heritable trait, then the fact that your grandmother has six male great grandchildren might suggest that she carries this gene and has passed it on to her descendants, and this in turn might suggest that the chance of any great grandchild of hers being male is greater than 50%.

    But you'd want to know a lot more. Were her children and her grandchildren disproportionately male? Do all of her descendants carry this gene or only some? Does such a gene even exist at all and, if it does, does she carry it?

    You can readily see that these are not maths questions; they are biology questions.

    If we adopt a mathematical model in which each birth is taken to be an independent event, then the chance that her next great-grandchild will be a boy is 50%.


  • #4
    timmy_mallet
    Closed Accounts Posts: 1,165 ✭✭✭timmy_mallet


    Yes. I understand that God may play a role, but I was really looking for a "coin toss" type answer. And in the end, the chance of it being a 6 boys 1 girl, is equally as likely as 7 boys. So, 50/50.


  • #5
    timmy_mallet
    Closed Accounts Posts: 1,165 ✭✭✭timmy_mallet


    learn_more wrote: »
    Do we take into account the probability that one of them might be homosexual?
    You wha'?!


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