# Probability formula

1. Given P(AnB)=0.6 and P(A|B)=0.10, find P(B)

2. P(A|B)=P(AnB)/P(B)

3. I plugged in the numbers in the formula but keep getting that P(B) is 6.... which is wrong since P cannot be greater than 0. Am I doing something wrong?

Mark44
Mentor
Instead of plugging in numbers, solve this equation algebraically for P(B):
P(A|B)=P(AnB)/P(B)

When you have P(B) isolated, substitute the values you have for the two other quantities.

That's what I did.

P(B)=P(AnB)/P(A|B)=0.6/0.1=6........but this makes no sense to me.

Mark44
Mentor
I don't see anything wrong in your work, although obviously a probability can't be larger than 1. Are you sure you have the problem written the same as it was given to you?