Question $14($Mandatory$)(10$ points$)$

$"$ 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, The technician claims he is always busy and asks for a big raise. What $\%$ of the time is he actually busy, overall? $"$

Question $14$ options:

$25$ percent of the time

$95$ percent of the time

$75$ percent of the time

$100$ percent of the time