Let RS (resp., RA) denote the average number of runs scored (resp., allowed) in a baseball game by a team. It was numerically observed years ago that a good predictor of a team's won-loss percentage is RS^2 / (RS^2 + RA^2), though no one knew WHY the formula worked. We review elementary concepts of probability and statistics and discuss how one can build and solve a model for this problem. In the course of investigating this problem we discuss how one attacks problems like this in general (what are the features of a good model, how to solve it, and so on). The only pre-requisite is simple calculus (no baseball knowledge is required, though Red Sox knowledge is always a plus). Speaker(s): Steven Miller (Williams College)