College Math

College Math Study Guide

Now, to find the probability that a white ball is drawn, there are two cases: White from urn 1 OR white from urn 2; that is P(W)= P(W∩T’) + P(W∩T) A ball is white from urn 1 is possible, when it is given that tails is not tossed, that is: P(W/T’) = P(W∩T’)/P(T’) P(W∩T’) = P(W/T’)* P(T’) = 5/12*1/2 = 5/24 A ball is white from urn 2 is possible, when it is given that tails is tossed, that is: P(W/T) = P(W∩T)/P(T) P(W∩T) = P(W/T)* P(T) = 3/15*1/2 = 1/10 Probability that a white ball is drawn = 5/24 + 1/10 = 0.3083 P((T|W) = P(T∩W)/P(W) = 0.1/0.3083 = 0.3432 = 34%

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