This is a genetic question: The Bionomial is a more complex calculation used when you have multiple events AND multiple outcomes. Use the following P (s of A, t of B) = ( N! ) ps qt S! T! BTW= s + t = n and p+q = 1 Here are problems that use this rule: 5. John and Mary each have sisters with cystic fibrosis. They would like to marry and have children, but are concerned that they too may have a child with cystic fibrosis. Cystic fibrosis is an autosomal recessive disease located on chromosome 7. If John and Mary are each heterozygous for cystic fibrosis what is the probability of: A. Having 2 normal children and 2 affected children in any order? B. Having 3 normal children and 2 affected children in any order?.