2001 AIME II Problems/Problem 9

Revision as of 14:14, 30 October 2007 by 1=2 (talk | contribs) (Problem)


Each unit square of a 3-by-3 unit-square grid is to be colored either blue or red. For each square, either color is equally likely to be used. The probability of obtaining a grid that does not have a 2-by-2 red square is $\frac {m}{n}$, where $m$ and $n$ are relatively prime positive integers. Find $m + n$.


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