Daughter Colorblind Question

[SaveTheRhinos]

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"A seemingly normal woman had a colorblind mother. She marries a colorblind man. What is the probability that her first daughter will be color blind?"

a) 0
b) 25
c) 50
d) 75
e) 100

The answer says 50% chance. Because Father is Xa Y and mother is XA Xa so daughters= XA Xa or Xa Xa.

I said 25% chance because while there is a 50% chance that she will be colorblind there is also a 50% chance that she would have son? so .5 x .5= .25. Am I right? or is the book right? what answer would I put on the DAT? Did I just over think?

Thanks
Rhino

 

[Dgeorg6]

It doesn't ask what is the chance she will have a colorblind daughter. It asks what is the chance her first daughter will be colorblind, thus forth you dont factor in the chance of her having a son

 

[SaveTheRhinos]

Makes sense, Thanks!

 

[sexysummer]

Why there is 50% chance her first daughter will be colorblind since there is only 1 XcXc and 1 XXc? Isn't the XcXc means colorblind as specified by the problem? Does the XcX get factored into the problem as well when counting the percent of colorblind people?

Also, why there is 50% chance for sons as well because there is only 1 XcY so 1/4 is 0.25 which is 25%, am I right?
Can anyone correct if I am wrong. please shed some light on

thanks

 

[Lnguyen7]

"A seemingly normal woman had a colorblind mother. She marries a colorblind man. What is the probability that her first daughter will be color blind?"

a) 0
b) 25
c) 50
d) 75
e) 100

The answer says 50% chance. Because Father is Xa Y and mother is XA Xa so daughters= XA Xa or Xa Xa.

I said 25% chance because while there is a 50% chance that she will be colorblind there is also a 50% chance that she would have son? so .5 x .5= .25. Am I right? or is the book right? what answer would I put on the DAT? Did I just over think?

Thanks
Rhino

Why there is 50% chance her first daughter will be colorblind since there is only 1 XcXc and 1 XXc? Isn't the XcXc means colorblind as specified by the problem? Does the XcX get factored into the problem as well when counting the percent of colorblind people?

Also, why there is 50% chance for sons as well because there is only 1 XcY so 1/4 is 0.25 which is 25%, am I right?
Can anyone correct if I am wrong. please shed some light on

thanks

The question asks specifically about her daughters, not her children. Out of two daughters, one will have colorbind. Thus, it is 50%. The same for sons.