Question

A couple plan to have exactly three children.
(a) Construct a tree diagram and list the sample space.
(b) Find the probability that the family has at least two girls.

Answer 1

hard to do a tree diagram here, but the sample space would be

BBB
BBG
BGB
BGG
.
.
.
GGG

"at least two" girls means either all girls or 2 girls and a boy.

count those cases and put over 8

Answer 2

Thanks Reiny, you are absolutly right.