At Joe's Billiard Hall they rent tables by the hour and also rent Balabushka billiard cues for purists that can't afford their own. The rental process for these cues is exhaustive and takes an hour and a half for each application. There are three leasing agents that conduct these interviews, and on average, it is one hour between customer arrivals. a. How busy are the servers on average? b. How many customers are either waiting or being served on average? c. What is the average time a customer spends in the system? d. What percentage of the time is the system completely empty? e. What is the likelihood there are more than three customers in the system?