Help on probability questions....
1.Suppose that the eye colour of a person is classified on the basis of one pair of genes
and that d represents a dominant gene and r a recessive gene. Thus a person with dd
genes is pure dominant (dark eye colour), one with rr is pure recessive (blue eye colour)
and one with rd is hybrid (and has dark eye colour). Children receive one gene from
each parent at random. If two hybrid parents have a total of four children, calculate the
probability that 2 of the 4 children have dark eyes.
2. A certain disease is only suffered by men and can only be transmitted by direct
inheritance from one's mother if she is a carrier. If a woman is a carrier the probability
that she transmits the disease to any one of her children (the boys being sufferers and
the girls carrier), is 0.5, independently of all other children. A woman knows that her
brother has the disease. If she already has two normal sons, what is the probability that
her next child will be unaffected?
I so bad at these could someone walk me through them.
and that d represents a dominant gene and r a recessive gene. Thus a person with dd
genes is pure dominant (dark eye colour), one with rr is pure recessive (blue eye colour)
and one with rd is hybrid (and has dark eye colour). Children receive one gene from
each parent at random. If two hybrid parents have a total of four children, calculate the
probability that 2 of the 4 children have dark eyes.
2. A certain disease is only suffered by men and can only be transmitted by direct
inheritance from one's mother if she is a carrier. If a woman is a carrier the probability
that she transmits the disease to any one of her children (the boys being sufferers and
the girls carrier), is 0.5, independently of all other children. A woman knows that her
brother has the disease. If she already has two normal sons, what is the probability that
her next child will be unaffected?
I so bad at these could someone walk me through them.
Original post by Righteouss
1.Suppose that the eye colour of a person is classified on the basis of one pair of genes
and that d represents a dominant gene and r a recessive gene. Thus a person with dd
genes is pure dominant (dark eye colour), one with rr is pure recessive (blue eye colour)
and one with rd is hybrid (and has dark eye colour). Children receive one gene from
each parent at random. If two hybrid parents have a total of four children, calculate the
probability that 2 of the 4 children have dark eyes.
and that d represents a dominant gene and r a recessive gene. Thus a person with dd
genes is pure dominant (dark eye colour), one with rr is pure recessive (blue eye colour)
and one with rd is hybrid (and has dark eye colour). Children receive one gene from
each parent at random. If two hybrid parents have a total of four children, calculate the
probability that 2 of the 4 children have dark eyes.
Each child has these choices
FdMd
FdMr
FrMd
FrMr
So an individual has 0.75 chance of having dark eyes
DDBB would, therefore have probability = 0.75*0.75*0.25*0.25
DBBD would also have probability = 0.75*0.25*0.25*0.75
you need to consider all the ways in which you could list 2 Dark and 2 Blue eyed children
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