Please need help!

And please give explanations to the answer, see option answers below.

Thank you!

A. 0.9

C. 4.5

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 administration finally increases the budget for the computer lab after numerous student protests, and the lab hires another technician who works at the same rate as the first echnician. What is the average waiting time per student with the 2 technicians working at the same time? Assume the students form a single line at the help desk, and continue to arrive at the average rate of 15/hr. Use formulas 0.9 min impossible to tell without additional information 4.5 min 9 min n