<s>[INST] There are 10 people at a party, and each person is either wearing a red shirt or a blue shirt. The distribution of shirts is such that each person's probability of wearing a red shirt can be modeled by the binomial distribution. Let $r$ be the number of people wearing red shirts, and let $D$ be the difference between the number of people wearing red shirts and the number of people wearing blue shirts (so that $r + b = 10$ and $D = r - b$). Okay so far?[/INST]