A Professor Decides to Hold a Three-Hour Window Open for Student

Essay

A professor decides to hold a three-hour window open for student advising.The professor has 15 advisees.He's unsure if each advisee will show up, and it's possible that a single advisee could show up multiple times during the 3-hour window.On average, the professor will spend 12 minutes with each student.He usually expects each student to arrive once during the 3-hour window.
(a)What proportion of the time can the professor expect to be busy during the window?
(b)What is the expected number of students in queue during the window?
(c)What is the expected wait time in queue during the window?