nbme 3 - appendicitis

[ArchivalUser]

mother has waardenburg syndrome{AD}her husband is unaffected and they plan to have a family with three children.what is the probability that one of the three children will be affected?
A.1/8
B.1/4
C.3/8
D.1/3
E.7/8

[ArchivalUser]

1/8..????

[ArchivalUser]

Agree with 1/8.

Mom is Aa, dad is aa--------Aa x aa-> Aa, Aa, aa, aa
To calculate one of the three children will be affected, it needs to meet this requirement:
one child being affected, the other two not. Chances are all 1/2, respectively.

so 1/2x1/2x1/2=1/8