probability of A given B.

HI; Just need to check if this is correct,Whats the probability of A given B?

P(A) = 1/2

P(B) = 1/2

*P*(*A *| *B*) = *P*(*A* ∩ *B*) / P(*B*).

*P*(*A* ∩ *B*) = P(A) + P(B) - *P*(*A* ∪ *B*).

= 3/6 + 3/6 – 4/6.

= 6/6 - 4/6.

= 2/6 = 1/3.

*P*(*A *| *B*) 1/3 / 3/6 = 1/3 * 6/3 = 6/9.

= 2/3.

Thanks.

Re: probability of A given B.

Quote:

Originally Posted by

**anthonye** HI; Just need to check if this is correct,Whats the probability of A given B?

P(A) = 1/2

P(B) = 1/2

*P*(*A *| *B*) = *P*(*A* ∩ *B*) / P(*B*).

*P*(*A* ∩ *B*) = P(A) + P(B) - *P*(*A* ∪ *B*).

= 3/6 + 3/6 – 4/6.

If all you were given is that "P(A)= 1/2" and "P(B)= 1/2" (above) where did you get "$\displaystyle P(A\cap B)= 4/6$?

Quote:

= 6/6 - 4/6. = 2/6 = 1/3.

*P*(*A *| *B*) 1/3 / 3/6 = 1/3 * 6/3 = 6/9. = 2/3.

Thanks.