Exam 17: Waiting Lines

A ________ is a single step in the service process.

What is a finite-source model? Give an example of its appropriate use.

Customers arrive according to a Poisson distribution.The average number of customer arrivals per hour is six.The probability that four customers will arrive in the next three hours is:

An operations manager organizes a process improvement team and the resulting process has a lower mean (µ).Which statement is the BEST description of this change?

A(n)________ is a rule that allows a customer of higher priority to interrupt the service of another customer.

With a multiple-server model,increasing the arrival rate by 10 percent and also increasing the service rate of each server by 10 percent will result in:

With a single-server model,increasing the promotions for a service through advertising will most likely:

A harvesting firm has six combines,each requiring service at an average rate of once every 40 hours,according to an exponential distribution.The firm has a mechanic who needs four hours to complete the average repair with exponential service times. a.What is the average utilization of the mechanic? b.What is the average number of combines in the system? c.What is the average number of combines in line? d.What is the average time spent being repaired and waiting? e.What is the average time spent in line waiting for repair?

The curtain goes up at 8 pm for the play "The Life and Times of A.K.Erlang." If the parameters in Scenario B.1 are at work,what's the latest a patron of the theater would want to arrive in order to be seated before the light dim,the curtain rises,and the actor playing A.K.Erlang takes his rightful place at center stage?

Scenario B.2 Weary travelers arrive at Will Rogers International Airport,pick up their luggage,stumble to their cars,and proceed to the parking lot attendant to pay for their parking.Traveler interarrival times are exponentially distributed,as are the service times of the attendant.On average,travelers arrive every 25 seconds.The attendant can process three travelers per minute,and processing rates follow a Poisson distribution. -Use the information in Scenario B.2.What is the average number of customers in the system?

The average lead time of a unit of product through a manufacturing station is 10 minutes.The production rate has been steady at five units per hour.The average work-in-process inventory at this station is:

Under the assumptions of waiting line models,it is impossible for management to affect the rate of customer arrivals.

Customer waiting times for a call center are extremely long.Two possible explanations for this phenomenon are low ________ or low ________.

Customers in a small retail store arrive at the single cashier at the rate of 10 per hour.The average service time for the cashier is five minutes.Arrivals tend to follow a Poisson distribution,and service times follow an exponential distribution. a.What is the average utilization of the cashier? b.What is the average number of customers in the system? c.What is the average number of customers in line? d.What is the average time spent in the system? e.What is the average time spent in line?

A professor sits in his office and answers questions from his students the afternoon before the final exam.His class is a mass lecture of 350 students,so he concentrates on providing explanations as quickly as possible.On average,he can answer 60 questions an hour and students arrive at his office every five minutes.Student arrivals are Poisson distributed,each student has only one question and answer times are exponentially distributed. a.What fraction of his time does the professor spend answering questions? b.What is the average number of students waiting outside his office? c.What is the average time a student spends in line outside the professor's office?

Scenario B.1 A single volunteer octogenarian usher can scan tickets with a handheld device and direct theater patrons to their seats at a rate of 30 per hour with an accuracy rate approaching 23%.On average,about twenty-five customers arrive every minute for assistance and always wait,regardless of how long the line gets.Arrivals are governed by the Poisson distribution and service is governed by the exponential distribution. -When not directing patrons to their seats,the octogenarian usher in Scenario B.1 sneaks in a little knitting.If she can knit one stitch every two seconds,how many stitches can she knit in an average hour of seating patrons?

What are priority rules? Provide examples and indicate why a manager would choose to adopt one over another.

The owner of a desktop publishing company has seven loyal clients who periodically require his services.The owner has:

Customers are serviced at a rate of four customers per hour according to an exponential distribution.What is the probability that customer service will require fewer than 30 minutes?

An operations manager decides that customers should be processed based on the anticipated duration of their request instead of their arrival time.The system has been changed in what fashion?