Imagine that a newly discovered, recessively inherited disease is expressed only in individuals with type o blood, although the disease and blood group are independently inherited.
a normal man with type a blood and a normal woman with type b blood have already had one child with the disease. the woman is now pregnant for a second time.
assuming that both parents are heterozygous for the gene that causes the disease, what is the probability that the second child will also have the disease? express your answer as a fraction using the slash symbol and no spaces (for example, 1/2).