There are 3 identical boxes: Box I has 2 gold coins, Box II has 2 silver coins, Box III has 1 gold and 1 silver coin. A box is chosen randomly and a coin is drawn. If it is gold, the probability the other coin in the box is also gold is:

There are 3 identical boxes: Box I has 2 gold coins, Box II has 2 silver coins, Box III has 1 gold and 1 silver coin. A box is chosen randomly and a coin is drawn. If it is gold, the probability the other coin in the box is also gold is:

• A. 1/2
• B. 1/3
• C. 2/3
• D. 3/4

Answer: C) 2/3

Explanation: This asks for P(Box I | Gold). P(Box I|G) = (1/3 × 1) / [(1/3 × 1) + (1/3 × 0) + (1/3 × 1/2)] = 1 / (1 + 1/2) = 2/3.