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Red and Black Cards

Probability puzzles require you to weigh all the possibilities and pick the most likely outcome.


Puzzle ID:#279
Fun:*** (2.46)
Difficulty:** (1.83)
Submitted By:jerry1***
Corrected By:absy




You have two cards, one red on both sides, one red on one side and black on the other. You reach into a hat and pull out one card, viewing only the top. It is red. What`s the probability that the other side is red?


The probability that it is red is 2/3. If you think of the 3 red sides as labeled r1, r2, and r3, then 2 of the 3 times you see a red card, it will be red on the other side.

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