# Math Help - really basic coin flip question

1. ## really basic coin flip question

Please confirm that I am doing this correctly:

What is the probability that a fair coin lands heads four times out of five flips?

I calculate this by doing the following:
Note that "5 choose 4" describes a binomial coefficient.

"5 choose 4" $*(1/2)^5=5*(1/32)=5/32$

which is 15.625%. Please confirm that this is correct. Thanks

2. Originally Posted by jmedsy
Please confirm that I am doing this correctly:

What is the probability that a fair coin lands heads four times out of five flips?

I calculate this by doing the following:
Note that "5 choose 4" describes a binomial coefficient.

"5 choose 4" $*(1/2)^5=5*(1/32)=5/32$

which is 15.625%. Please confirm that this is correct. Thanks
Yes

$P(Y=4)=\left(\begin{array}{cc}5\\4\\\end{array}\ri ght)(0.5)^{4}(1-0.5)^{5-4}=0.15625$