# Math Help - Math Contest Problem 3

1. ## Math Contest Problem 3

This problem is from the 2002 Luzerne County Math Contest:
Assume a person flips five fair coins. What is the probability of obtaining at least 4 heads?
Is there any way to do this problem without listing all the possibilites? Thanks in advance!

2. Originally Posted by eric1299171
This problem is from the 2002 Luzerne County Math Contest:
Assume a person flips five fair coins. What is the probability of obtaining at least 4 heads?
Is there any way to do this problem without listing all the possibilites? Thanks in advance!
The number of heads in five flips is a binomial random variable $X \sim B(5,0.5)$, and you are asked to find:

$p=Pr(X=5)+Pr(X=4)$

CB

3. Thanks for the reply! I looked up the formula in a probability book I had. =)