# Venn diagrams

• May 7th 2011, 11:23 PM
qwertyuiop
Venn diagrams
Hey guys

I got a question with Conditional probability and i want to display this on a Venn diagram.

Pr(A|B) = 1/3
Pr(A|B') = 3/4
Pr(B) = 2/5
Pr(A'nB')=1/10

Initially i used the rule and i got Pr(AnB) = 2/15

but then i tried to do it on a Kanaugh map to test it, it seems to be wrong.

• May 7th 2011, 11:34 PM
mr fantastic
Quote:

Originally Posted by qwertyuiop
Hey guys

I got a question with Conditional probability and i want to display this on a Venn diagram.

Pr(A|B) = 1/3
Pr(A|B') = 3/4
Pr(B) = 2/5
Pr(A'nB')=1/10 Mr F says: This value is NOT consistent with the above data.

Initially i used the rule and i got Pr(AnB) = 2/15

but then i tried to do it on a Kanaugh map to test it, it seems to be wrong.

Why would you use a Karnaugh table? A tree diagram is clearly the prefered approach because of the information given about the conditional probabilities. The answer of 2/15 is consistent with

Pr(A|B) = 1/3
Pr(A|B') = 3/4
Pr(B) = 2/5
• May 7th 2011, 11:50 PM
qwertyuiop
so there's something wrong with the question ?
• May 8th 2011, 03:01 AM
mr fantastic
Quote:

Originally Posted by qwertyuiop
so there's something wrong with the question ?

Well, if Pr(A'nB')=1/10 is part of the question, then yes that would be the obvious conclusion from what I wrote earlier.