Friday Puzzle

Adapted from a Richard Wiseman post:

From a normal playing deck of 52 cards, 4 cards are pulled at random and placed face down on a table. IF it is the case that by picking any two of those selected cards at random, the chance of getting 2 red cards is 50%, then what is the chance of picking, at random, two black cards from the 4?
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answer: 0% (for there to be a 50% chance of getting 2 red cards, there MUST be 3 red cards and 1 black card total)