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counting and probability senior

Problem

There are two cards; one is red on both sides and the other is red on one side and blue on the other. The cards have the same probability (1/2) of being chosen, and one is chosen and placed on the table. If the upper side of the card on the table is red, then the probability that the under-side is also red is
(A)
(B)
(C)
(D)
Solution
There are three red faces, and two are on the card that is completely red, so our answer is , which is .
Final answer
D