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anonymous
 4 years ago
hi. if A is the event that a lie detector test says that a given person is lying. B is that the person is truly lying. only information provided is:
P(AB) = 0.85
P(not Anot B ) = 0.70
P(B) = 0.35.
what is P(BA) ?
thanks for your help!
anonymous
 4 years ago
hi. if A is the event that a lie detector test says that a given person is lying. B is that the person is truly lying. only information provided is: P(AB) = 0.85 P(not Anot B ) = 0.70 P(B) = 0.35. what is P(BA) ? thanks for your help!

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anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0we can do this i think

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0\[P(BA)=\frac{P(A\cap B)}{P(A)}\] so we need these numbers on the right. now we know that \[P(A\cap B)=P(AB)P(B)=.85\times .35=.2957\] so all we need is the denominator \[P(A)\] to be done

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0\[P(A)=P(AB)P(B) + P(AB^c)P(B^c)\] and we know 3 out of these 4 numbers we just don't know \[P(AB^c)\] btw i bet this is under the heading of Baye's formula which is \[P(BA)=\frac{P(A\cap B)}{P(A)}=\frac{P(AB)P(B)}{P(AB)P(B) + P(AB^c)P(B^c)}\]

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0\[P(A^c\cap B^c)=P(A^cB^c)P(B^c) P(B^c)=.7\times .65=.455\]

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.0Are these independent events? if so, the P(AB=P(A)

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0no i don't think they are independent, buy we could check. in any case we see from the above that \[P(A)=.4925\] and so we are done.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0a picture makes this much easier.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0thanks for your suggestions:)
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