If you look carefully at the formulas in this chapter for all four unlimited population models, you can verify that for each one, L = λW and Lq = λWq. These are instances of the more general relationship known as Little’s Law, which states that for any steady state system, inventory equals average flow rate times average flow time. An advantage of using Little’s Law is that we don’t need to know the distributions of either the arrival process or the service process, the number of servers, or even the service priority rules. Given the relationship, if you know two of the values, then it is straightforward to solve for the third. For example, suppose that on average, Freddie’s Fast Fish has approximately 500 pounds of fish in cold storage. Freddie cooks and serves about 150 pounds of fish each day. Using Little’s Law, how long does the fish stay in storage on average?