Marcus and his brother always argue about who will walk the dog. Their father wants to find a random way of deciding who will do the job. He invented a game to help them decide. Each boy will have a bag with three
colored blocks in it: one yellow, one green, and one white. Each night before dinner, each boy draws a block out
of his bag. If the colors match, Marcus walks the dog. If the two colors do not match, his brother walks the dog.
Marcus's father wants to be sure that the game is fair. Help him decide.
What is the probability of the boys matching the same block?