what's the ans between 2.25 or 15 ?

Question 9 10 points Save During finals week, students arrive randomly at the help desk of the computer lab. There is only one technician due to budget cuts, and the time required to provide service varies from student to student. The average arrival rate is 15 students per hour, and the average service rate is 20 students per hour. Assuming standard waiting line distribution parameters hold, what is the average number of students in the line? " Use Multiple servers, Ave. #in Line' table 20 students 225 students 5 students 15 students