MathDB
Math Prize 2013 Problem 11

Source:

September 10, 2013
probability

Problem Statement

Alice throws two standard dice, with AA being the number on her first die and BB being the number on her second die. She then draws the line Ax+By=2013Ax + By = 2013. Boris also throws two standard dice, with CC being the number on his first die and DD being the number on his second die. He then draws the line Cx+Dy=2014Cx + Dy = 2014. Compute the probability that these two lines are parallel.