If a heterozygous woman without hemophilia had children with a man with hemophilia, what is the chance that their first child will have the disease?

1/2

Explanation:

let the alleles of the heterozygous woman without hemophilia be = Xhx

And the alleles of the man with hemophilia be XhY

If both XhY * Xhx; we have:

Xh Y

Xh XhXh XhY

x Xhx xY

XhXh and XhY are affected by the diseases

Xhx is a carrier

xY is normal

∴ the probability (chance) that their first child will have the disease is 2/4 of the total offspring

=1/2

∴ the probability (chance) that their first child will have the disease is 1/2