SOLUTION: Could use some help with this please. If P( A and B)=0.40 and P(A)=0.20 what is the value of P(B|A)? What is wrong with this question? Thank you for your time

Algebra ->  Probability-and-statistics -> SOLUTION: Could use some help with this please. If P( A and B)=0.40 and P(A)=0.20 what is the value of P(B|A)? What is wrong with this question? Thank you for your time      Log On


   

Question 742030: Could use some help with this please.
If P( A and B)=0.40 and P(A)=0.20 what is the value of P(B|A)? What is wrong with this question?
Thank you for your time
Answer by Edwin McCravy(20064) About Me  (Show Source):
You can put this solution on YOUR website!

1. First reason why the problem is flawed:

P(B|A) = %22P%28B_and_A%29%22%2F%22P%28A%29%22 = %22P%28A_and_B%29%22%2F%22P%28A%29%22 = .40%2F.20 = 2.

That's impossible because all probabilities are between 0 and 1.

2. Second reason why the problem is flawed:

P(A and B) can never be greater than P(A) or greater than P(B),

yet we are given the impossible case P(A and B)=0.40 and P(A)=0.20  

Edwin