The probability of drawing a pair of cards from a standard deck of 52 and having those cards be different colors is 26/51, slightly over 50%.
What is the smallest number of cards that need to be removed from the deck so that the probability of drawing a mismatched pair is exactly 50%?
(In reply to
Triangles (solution) by Jer)
please see my "the odds stay unchanged" problem of 2004
Ady