If a woman is a carrier of hemophilia and marries a normal male, the chances that their son will have hemophilia can be determined by considering the inheritance pattern of the sex-linked trait.
In this case, since hemophilia is a sex-linked trait, it is located on the X chromosome. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
If the woman is a carrier, it means that she has one normal X chromosome and one X chromosome with the hemophilia gene (Xh). The normal male, on the other hand, has one X chromosome and one Y chromosome, neither of which carries the hemophilia gene.
To determine the chances of their son having hemophilia:
The son would inherit one X chromosome from his mother.
If he receives the normal X chromosome (X), he will not have hemophilia.
If he receives the X chromosome with the hemophilia gene (Xh), he will have hemophilia.
Since the father only has one X chromosome to contribute, the son has a 50% chance of inheriting the X chromosome with the hemophilia gene (Xh) from his carrier mother. Therefore, the chances that their son will have hemophilia is 50%.
It's important to note that daughters of a carrier mother and a normal father would have a 50% chance of being carriers themselves, but the trait would not be expressed in them as severely as in affected males.