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Genetic Probability (Binomial Expansion)

  1. Feb 3, 2013 #1
    1. The problem statement, all variables and given/known data

    I'm stuck on a problem with two variables in it. The question wants to know what's the probability of getting 2 boys and 2 girls, with one of the boys being albino. They say one parent is albino and the other is a heterozygous carrier, so the change of getting it is 50% in the children.
    So by binomial expansion, it's 1 4 6 4 1. I know the two girls and two boys is the middle term with 6(p^2)(q^2) but with q and p being getting a boy or girl at .50 each. But how do I encompass the albino probability in this? Multiply each child by .50?

    2. Relevant equations

    (p^4)+4(p^3)(q)+6(p^2)(q^2)+4(q)(p^3)+(q^4)

    3. The attempt at a solution
    I can easily find the probability of getting two girls and two boys, I would simply use the 6(p^2)(q^2) with p and q being .50 respectively. I just don't know how to factor in the albino part.
     
  2. jcsd
  3. Feb 4, 2013 #2

    AGNuke

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    Gold Member

    Something like that. You should multiply with another binomial probability regarding the 4 children with "albino chromosome".
     
  4. Feb 4, 2013 #3

    Ygggdrasil

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    2015 Award

    It might be easier to calculate the probability that the two girls lack albinism and the probability that one of the boys has albinism.
     
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