A couple decides to have 4 children. If they succeed in having 4 children and each child is equally likely to be a boy or a girl, What is the probability that they will have exactly 3 girls and 1 boy?  Pick:
A) 4  B) 3  C) 2  D) 1  E) 1/2
Sample space = 2^4 = 16.   Favourable events = {bbgg}, {bgbg}, {bggb}, {ggbb}, {gbgb}, {gbbg}.{bggg},{gbbb)   Probability = 8/16 = 1/2.   Ans (1/2).
<result>E</result>
A couple decides to have 4 children. If they succeed in having 4 children and each child is equally likely to be a boy or a girl, What is the probability that they will have exactly 3 girls and 1 boy?