MathDB
Plant Probability

Source:

December 19, 2005
probabilitycountingdistinguishabilitysymmetry

Problem Statement

A gardener plants three maple trees, four oak trees, and five birch trees in a row. He plants them in random order, each arrangement being equally likely. Let mn\frac{m}{n} in lowest terms be the probability that no two birch trees are next to one another. Find m+nm + n.