So I was solving some biology questions, and this question left me confused. The response is supposed to be 22% according to the answers, but all the methods that I used did not lead me to it. I really hope that somebody can help me with it, the question sounds as follows:
Human ABO blood type is determined by two genes (H and I). First, the H gene codes for the antigen precursor. The dominant allele (H) leads to expression of the precursor; the recessive allele (h) does not. Second, the I gene has three allele forms, IA, IB and i, and determines blood type (A, B, O or AB).
A male with blood type A and a female with blood type B marry. Each of them is heterozygous for both the H gene and the I gene. What is the probability of having a son with blood type O? Give your answer as a percentage (%) rounded to an integer (without any decimals).