SOLUTION: If P(A) = 0.2, P(B) = 0.32, and P(A and B) = 0.01, then P(A|B) = ? I have tried P(A|B) = P(B and A)/ P(B) Meaning: 0.32 * 0.2 = .064 / 0.32 = .2 I'm not sure if this is co

Algebra ->  Probability-and-statistics -> SOLUTION: If P(A) = 0.2, P(B) = 0.32, and P(A and B) = 0.01, then P(A|B) = ? I have tried P(A|B) = P(B and A)/ P(B) Meaning: 0.32 * 0.2 = .064 / 0.32 = .2 I'm not sure if this is co      Log On


   



Question 1124047: If P(A) = 0.2, P(B) = 0.32, and P(A and B) = 0.01, then P(A|B) = ?
I have tried P(A|B) = P(B and A)/ P(B)
Meaning: 0.32 * 0.2 = .064 / 0.32 = .2
I'm not sure if this is correct but I got it wrong when I first submitted it so I'm assuming something isn't right here. I'm just trying to follow what my textbook gave me but I keep getting it wrong anyway..?

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

P(A and B) = P(B and A) = 0.01
P(B) = 0.32

P(A|B) = P(A and B)/P(B)
P(A|B) = 0.01/0.32
P(A|B) = 0.03125 which is the final answer

Round that value however you need to. Note how P(A) isn't used at all since we know for certain that event B has happened, we don't worry about the event solely based on A. Though we do deal with event A partially when it comes to P(A and B).