A Man Whose Mother Had Cystic Fibrosis (Autosomal Recessive)marries a Phenotypically

Essay

A man whose mother had cystic fibrosis (autosomal recessive)marries a phenotypically normal woman from outside the family,and the couple considers having a child.
a)If the frequency of cystic fibrosis heterozygotes (carriers)in the general population is 1 in 25,what is the chance that the first child will have cystic fibrosis?
b)If the first child does have cystic fibrosis,what is the probability that the second child will be normal?