Reversing conditional probability











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If



$$
P(B|A)=frac{P(A cap B)}{P(A)}
$$



then can the conditional probability be reversed ?



So that :



$$
P(A|B)=frac{P(B cap A)}{P(A)}
$$










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  • 1




    Just change the $P(A)$ in the denominator to $P(B)$, too.
    – Parcly Taxel
    Nov 17 at 14:11










  • Your "If" condition is always true and, of course, by symmetry, it can be reversed.
    – Arnaud Mégret
    Nov 17 at 15:18










  • Both equations are true only if $P(A)=P(B)neq 0$
    – callculus
    Nov 17 at 17:39















up vote
0
down vote

favorite












If



$$
P(B|A)=frac{P(A cap B)}{P(A)}
$$



then can the conditional probability be reversed ?



So that :



$$
P(A|B)=frac{P(B cap A)}{P(A)}
$$










share|cite|improve this question


















  • 1




    Just change the $P(A)$ in the denominator to $P(B)$, too.
    – Parcly Taxel
    Nov 17 at 14:11










  • Your "If" condition is always true and, of course, by symmetry, it can be reversed.
    – Arnaud Mégret
    Nov 17 at 15:18










  • Both equations are true only if $P(A)=P(B)neq 0$
    – callculus
    Nov 17 at 17:39













up vote
0
down vote

favorite









up vote
0
down vote

favorite











If



$$
P(B|A)=frac{P(A cap B)}{P(A)}
$$



then can the conditional probability be reversed ?



So that :



$$
P(A|B)=frac{P(B cap A)}{P(A)}
$$










share|cite|improve this question













If



$$
P(B|A)=frac{P(A cap B)}{P(A)}
$$



then can the conditional probability be reversed ?



So that :



$$
P(A|B)=frac{P(B cap A)}{P(A)}
$$







probability conditional-probability






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 17 at 14:06









blue-sky

96511222




96511222








  • 1




    Just change the $P(A)$ in the denominator to $P(B)$, too.
    – Parcly Taxel
    Nov 17 at 14:11










  • Your "If" condition is always true and, of course, by symmetry, it can be reversed.
    – Arnaud Mégret
    Nov 17 at 15:18










  • Both equations are true only if $P(A)=P(B)neq 0$
    – callculus
    Nov 17 at 17:39














  • 1




    Just change the $P(A)$ in the denominator to $P(B)$, too.
    – Parcly Taxel
    Nov 17 at 14:11










  • Your "If" condition is always true and, of course, by symmetry, it can be reversed.
    – Arnaud Mégret
    Nov 17 at 15:18










  • Both equations are true only if $P(A)=P(B)neq 0$
    – callculus
    Nov 17 at 17:39








1




1




Just change the $P(A)$ in the denominator to $P(B)$, too.
– Parcly Taxel
Nov 17 at 14:11




Just change the $P(A)$ in the denominator to $P(B)$, too.
– Parcly Taxel
Nov 17 at 14:11












Your "If" condition is always true and, of course, by symmetry, it can be reversed.
– Arnaud Mégret
Nov 17 at 15:18




Your "If" condition is always true and, of course, by symmetry, it can be reversed.
– Arnaud Mégret
Nov 17 at 15:18












Both equations are true only if $P(A)=P(B)neq 0$
– callculus
Nov 17 at 17:39




Both equations are true only if $P(A)=P(B)neq 0$
– callculus
Nov 17 at 17:39















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