# Finding Probability

• Oct 6th 2012, 03:12 PM
Solid8Snake
Finding Probability
I am experiencing difficulties with the following problem. I don't know how to find the intersection probability of Pr(AnBcomplement). This is just for the first row. I found intersection of a and b which is 0.4, I also found A complement which is 0.3 and b complement which 0.4. Any help would be greatly appreciated.
• Oct 6th 2012, 03:33 PM
MathTutor2013
Re: Finding Probability
Hi,

Notation: B* = complement of B

Remember that you can use: P(A) = P(A and B*) + P(A and B)

For example for the first row:

we know: Pr(A) = 0.7, Pr(B)=0.6 and Pr(AUB)=0.9

P(AUB) = P(A)+P(B)-P(A and B)

0.9 = 0.7+0.6 -P(A and B)

P(A and B) = 0.4

P(A and B*) = P(A)-P(A and B) = 0.7 - 0.4 = 0.3

P(B and A*) = P(B)- P(B and A) = 0.6 -0.4 = 0.2

Let me know if you need more help
• Oct 6th 2012, 03:39 PM
Plato
Re: Finding Probability
Quote:

Originally Posted by Solid8Snake
I am experiencing difficulties with the following problem. I don't know how to find the intersection probability of Pr(AnBcomplement). This is just for the first row. I found intersection of a and b which is 0.4, I also found A complement which is 0.3 and b complement which 0.4. Any help would be greatly appreciated.

That is a bad file. Word will not open it. Just type out your question.
• Oct 6th 2012, 03:57 PM
MathTutor2013
Re: Finding Probability

Thanks
• Oct 6th 2012, 05:01 PM
Plato
Re: Finding Probability
Quote:

Originally Posted by MathTutor2013

@MathTutor2013
I take it from your screen name you fancy yourself a tutor for mathematics.
Then why don't you bother to learn the standard mathematics protocol for mathematics type-setting LaTeX?
Don't you think that $P(A\cup B) = P(A)+P(B)-P(A\cap B)$ looks much more professional that P(AUB) = P(A)+P(B)-P(A and B)?

That code is simple [TEX]P(A\cup B) = P(A)+P(B)-P(A\cap B)[/TEX].

On the tool bar the $\Sigma$ gives the [TEX] [/TEX] wrap.

You can use this as a reference.
• Oct 7th 2012, 01:09 PM
Solid8Snake
Re: Finding Probability
Thank you very much, it's all clear now.