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Probabilities
Posted:
Mar 13, 2007 11:26 AM


Hi all,
I've got the following phrase:
BABAAAAAABAAABBAAAAAABA
I would like to calculate the conditional probability P(BA). If I use a logical thought, I get:
P(BA) = the_number_of_AB / the_number_of_A = 4 / 17 = 0.23
and if I use the formula P(BA) = P(B inter A)/P(A) I get: P(B inter A) = 4 / (231) and P(A) = 17/23 then:
P(BA) = 4/22 * 23/17 = 0.25
So I would like to know why the "logical thought" is wrong and if the result is right with the formula.
Thanks a lot



