biology
posted by katt0109 .
A couple has four children. What is the probability that there will be 2 boys and 2 girls? Assume that no outside forces influence the births.

Here are the ways it can happen:
all boys, only one way.
bbbb
three boys, one girl, four ways:
bbbg
bbgb
bgbb
gbbb
2girls, two boys six ways.
ggbb
gbgb
gbbg
bggb
bgbg
bbgg
three g, one boy, same as 3b,one g four ways.
four girls
gggg one way.
so probaby of two girls, two boys..
= six/total ways=6/16= 3/8