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not to be republished
PROBABILITY      541
Now
P(E) = P (black ball in first draw) = 10
15
Also given that the first ball drawn is black, i e , event E has occurred, now there
are 9 black balls and five white balls left in the urn Therefore, the probability that the
second ball drawn is black, given that the ball in the first draw is black, is nothing but
the conditional probability of F given that E has occurred