Virtually every business seeks to increase its profit from customers, but few business executives realize that a universal principle governs their customer profitability. They may be applying the 80/20 rule to sales, quality control, investing, production, or other business functions without realizing that the 80:20 ratio actually summarizes the Pareto distribution of inputs to outputs. According to his equilibrium theory of relationships, stability is reached when inputs in the top 20% generate 80% of the outputs while inputs in the bottom 80% generate 20% of the outputs. Recently mathematicians confirmed that the Pareto distribution is as universal as the normal "bell-shaped" distribution, but is log linear and predicts results, rather than probabilities.