a girl flipped a coin 4 times, what is the probability that she gets 3 heads and 1 tails? Using a tree diagram

I searched Google under the key words "tree diagram probability" to get this:

http://www.google.com/search?client=safari&rls=en&q=tree+diagram+probability&ie=UTF-8&oe=UTF-8

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.