# Math Help - Simple probability Q

1. ## Simple probability Q

Hi guys,

I came across this question, and couldnt figure out how he arrived at the answer. So i am hoping someone can help me...

onsider a job interview situation to be a random experiment. Define two events: Event A : the candidate had good eye contact
Event B : the candidate got the job.
Assume that
P(A) = 0.40
P(B) = 0.20
P(A and B) = 0.12

P(A|B) = (P(A and B) / P(B) = 0.12 / 0.20 = 0.6
P(B|A) = (P(A and B) / P(A) = 0.12 / 0.40 = 0.3

Calculate the probability of candidate getting the job WITHOUT good eye contact?

Supplied Ans:
P(B|Not A) = P(B and Not A) / P(Not A) = 0.08 / 0.6 = 0.13

How was P(B and Not A) = 0.08 calculated?
Thanks for any help given....

2. ## Re: Simple probability Q

Notation: $A^c$ is not $A$,

$\mathcal{P}(B)=\mathcal{P}(B\cap A)+\mathcal{P}(B\cap A^c)$

3. ## Re: Simple probability Q

Originally Posted by Plato
Notation: $A^c$ is not $A$,

$\mathcal{P}(B)=\mathcal{P}(B\cap A)+\mathcal{P}(B\cap A^c)$
Thank you SO much