Mini$-$case for the next three questions:

Swift Sage Solutions $($SSS$),$ comfortably located in the heart of downtown Houston, is a coaching service for high school students. Since hiring some exceptional graduate students $($from the University of Houston and Rice University$)$ as coaches recently, SSS has enjoyed positive reviews from high school students. Even if SSS is busy and their office becomes crowded, they do not limit the number of high school students entering during their regular operating hours. Even with large crowds, they tend to operate on an M$/$M$/1$ model, focusing on those coming in first getting served first $-$ in the order of arrivals. On any given day, SSS sees one student show up every five minutes, and the mentors coach about $15$ students per hour.