Supposed (as is roughly correct) that each child born is equally likely to be a boy or a girl and that sexes of successive children are independent. If we let BG mean that the older child is a boy, and the younger child is a girl, then each of the combinations BB, BG, GB, GG has probability 0.25. Ashley and Brianna each have two children.
a.) You know that at least one of Ashley's children is a boy. What is the conditional probability that she has two boys?
b.) You know that Brianna's older child is a boy. What is the conditional probability that she has two boys?
please help, if you can :)
Statistics - Mgraph, Sunday, May 29, 2011 at 11:11am
The formula of the conditional probability
a)Y="at least one is a boy"
If X then Y => XY=X P(XY)=P(X)=1/4
b)Y="the older child is a boy"
X=BB, XY=X, P(XY)=1/4