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Math Help - Conditional Probability rule?

  1. #1
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    Conditional Probability rule?

    Say I have P(A | B)
    and I want to find P(A | Bc)
    where Bc is B complement

    does that mean
    P(A | Bc) = 1 - P(A | B)?

    if not, how would i do it?
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  2. #2
    Senior Member Danneedshelp's Avatar
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    Quote Originally Posted by helpwithassgn View Post

    P(A | Bc) = 1 - P(A | B)?

    if not, how would i do it?
    P(A|\bar{B})=\frac{P(A\cap\bar{B})}{P(\bar{B})}=\f  rac{P(\bar{B})-P(\bar{A}\cap\bar{B})}{P(\bar{B})}=1-P(\bar{A}|\bar{B})
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  3. #3
    MHF Contributor matheagle's Avatar
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    IF you have independence between A and B then you also have

     P(A|\bar B)=P(A)=P(A|B)
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  4. #4
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    Thanks!
    Makes sense.
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