Teacher2Teacher Q&A #3784

Tree diagram: Four Children (2B's/2G's any order)

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From: Judy Bellonio
To: Teacher2Teacher Service
Date: Apr 24, 2000 at 18:27:36
Subject: Tree diagram: Four Children (2B's/2G's any order)

I am teaching my students how to make a tree diagram. The problem that I will be discussing is the probability of a particular sequence of boys and girls when there are four children. I know that the probability of having a boy 1st is 1/2, of having a girl last is 1/2, of having four boys is 1/16, of having four girls is 1/16 and I understand the formulas associated with these. The problem that I can not get the formula for is the probability of having two boys and two girls in any order. I know the answer is 6/16 by using a tree diagram. My question is, is there a mathematical formula to figure this out?

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