[finty]

Hey,
Currently revising for my S1 exam,everything is going better that expected so far, only things I have trouble with are some discrete random variable questions and some probability questions.

One thing I can't find an anwer for though. This may be a stupid question but I'll ask anyway as it is confusing me.

Does P(A|B) = P(B|A)?

I thought they would be too different values but a marks scheme I have here seems to indicate differently, or maybe I am just not understanding it right.

Thanks for any help .

[Olibert]

Shouldn't do.

Although i'm not great with probability. I just tried an example if both values for A and B were the same and it's 2 which can't be correct since probabilities are between 0 and 1

[yusufu]

Originally Posted by finty

Hey,
Currently revising for my S1 exam,everything is going better that expected so far, only things I have trouble with are some discrete random variable questions and some probability questions.

One thing I can't find an anwer for though. This may be a stupid question but I'll ask anyway as it is confusing me.

Does P(A|B) = P(B|A)?

I thought they would be too different values but a marks scheme I have here seems to indicate differently, or maybe I am just not understanding it right.

Thanks for any help .

Not true in general.

[modini]

They are not same value. This is because, if A and B overlap and there is a number in the middle, P(A|B) means what's the probablility of A when just looking at B. P(B|A) means what's the probability of B when just looking at A. This is referring to the middle overlap bit but you have to write the overlap bit as a fraction of either A or B so they are not the same

However if A and B are the same value then yes P(A|B) = P(B|A)

(I hope I'm write anyway lol )