Poker Party
originally published on January 18, 2010
So, you’ve got 104 cards all shuffled together. Then you split them back into two equal piles. Well, you haven’t looked at them now, in the traditional manner. You just counted them out so you have a pile of 52 on one side–we’ll call that pile A–and a pile of 52 cards – pile B — on the other side, and they’re all mixed up. Here’s the question: What are the chances that the number of red cards in pile A equals the number of black cards in pile B? And question 2, or B: How many cards do you have to look at to be sure of your answer?
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April 20th, 2011 | Category: 
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I assume the 104 cards are two full decks, each deck consisting of 26 red and 26 black cards. That being the case, the number of red cards in deck A will always match the number of black cards in deck B. Blindly changing five cards from A with five from B will result in each having the same number of red vs. black cards and vice versa. There would be no need to check since the red/black numbers will always match.
You are correct!
The answers are 100% and None, respectively.
You are today’s winner.