Gene problem - X-linked?

Question

Hemophilia is inherited as an X-linked recessive. A woman has a brother with this defect and a mother and father who are phenotypically normal. What is the probability that this woman will be a carrier if she herself is phenotypically normal?

Answer 1

50 percent. Details: Mom = xX, Dad = XY. Brother = xY. (the little x is the "bad" one.) So sister gets either XX or xX. (The X on the left is from Mom, the X on the right is from Dad.)