A couple has already had 3 girls with cystic fibrosis, and were hoping to have a normal child for their fourth.What are the chances that the fourth child will be a normal male?
A) 0
B) 1/8
C) 1/4
D) 3/8
E) 1/2

Question

Quizplus · Accepted Answer

Cystic fibrosis is an autosomal recessive disorder. The parents are both carriers, since they have had 3 affected children. The probability of having a normal male child is 1/4.

A Couple Has Already Had 3 Girls with Cystic Fibrosis