Urn A has 2 White and 3 Black balls. Urn B has 3 White and 2 Black balls. A fair coin is tossed; if Head appears Urn A is chosen, otherwise Urn B. A ball is drawn and found Black. The probability that Head appeared is:

Urn A has 2 White and 3 Black balls. Urn B has 3 White and 2 Black balls. A fair coin is tossed; if Head appears Urn A is chosen, otherwise Urn B. A ball is drawn and found Black. The probability that Head appeared is:

• A. 2/5
• B. 3/5
• C. 1/2
• D. 1/4

Answer: B) 3/5

Explanation: P(Head|Black) = (1/2 × 3/5) / [(1/2 × 3/5) + (1/2 × 2/5)] = (3/10) / (5/10) = 3/5.