Exam 24: Waiting-Line Models

A crew of mechanics at the Highway Department garage repair vehicles that break down at an average of λ = 8 vehicles per day (approximately Poisson in nature).The mechanic crew can service an average of μ= 11 vehicles per day with a repair time distribution that approximates an exponential distribution.The crew cost is approximately $300 per day.The cost associated with lost productivity from the breakdown is estimated at $150 per vehicle per day (or any fraction thereof).Which is cheaper,the existing system with one service crew,or a revised system with two service crews?

Suppose that a fast food restaurant wants the average line to be 4 customers and that 80 customers arrive each hours.How many minutes will the average customer be forced to wait in line?

A copy centre has five machines that serve many customers throughout the day;the waiting-line system for copy service has an infinite population while the waiting-line system for copier maintenance has a finite population.

What is queue discipline? State three rules for queue discipline.Which of these rules appears most frequently in the four main models?

Which of the following is a measure of queue performance?

A university has several technicians in the repair station to care for the computers in the student labs.This system is most likely

What does it mean to have a patient customer in a waiting line?

Which of the following is not a measure of a queue's performance?

Suppose that 1 customer arrives each minute in a Poisson distribution.Is it more likely that 2 customers or 0 customers will arrive each minute?

Which of the following represents a customer that reneged due to the waiting-line?

A single-phase waiting-line system meets the assumptions of constant service time or M/D/1.Units arrive at this system every 12 minutes on average.Service takes a constant 8 minutes.The average length of the queue is approximately

Four of the most widely used waiting line models-M/M/1 or A,M/M/S or B,M/D/1 or C,and Limited population or D-all share three characteristics: Poisson arrivals,FIFO discipline,and exponential service times.

Which of the following is most likely to be served in a last-in,first-served (LIFS)queue discipline?

What are Ls and Lq,as used in waiting line terminology? Which is larger,Ls or Lq? Explain.

The study of waiting lines calculates the cost of providing good service but does not value the cost of customers' waiting time.

Which part of a waiting line has characteristics that involve statistical distribution?

Students arrive randomly at the help desk of the computer lab.There is only one service agent,and the time required for inquiry varies from student to student.Arrival rates have been found to follow the Poisson distribution,and the service times follow the negative exponential distribution.The average arrival rate is 12 students per hour,and the average service rate is 20 students per hour.A student has just entered the system.How long is she expected to stay in the system?

Study of waiting-line models helps operations managers better understand

Which of the following is most likely to violate a FIFO queue?

Which of the following is a requirement for application of Little's Law to be valid?