Practical Management Science
5th Edition
ISBN: 9781305734845
Author: WINSTON
Publisher: Cengage
expand_more
expand_more
format_list_bulleted
Concept explainers
Question
Chapter 13, Problem 46P
Summary Introduction
To determine: The number of postal windows that should be opened to minimize the hourly costs.
Introduction: In order to predict the waiting time and length of the queue, queueing model will be framed. Queueing theory is the mathematical model that can be used for the decision-making process regarding the resources required to provide a service.
Expert Solution & Answer
Explanation of Solution
Model:
Formulae to determine the model:
Three postal windows should be opened in order to minimize the hourly costs
Want to see more full solutions like this?
Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
An average of 90 patrons per hour arrive at a hotel lobby(interarrival times are exponential), waiting to check in. At
present, there are 5 clerks, and patrons are waiting in a singleline for the first available clerk. The average time for a clerkto service a patron is 3 minutes (exponentially distributed).Clerks earn $10 per hour, and the hotel assesses a waitingtime cost of $20 for each hour that a patron waits in line.a Compute the expected cost per hour of the currentsystem.b The hotel is considering replacing one clerk with an
Automatic Clerk Machine (ACM). Management esti-mates that 20% of all patrons will use an ACM. An
ACM takes an average of 1 minute to service a patron.It costs $48 per day (1 day 8 hours) to operate anACM. Should the hotel install the ACM? Assume thatall customers who are willing to use the ACM wait in asingle queue.
Customers arrive randomly to an airport shoe-shine stand with only ONE attendant at a rate of 8 per hour. The
average length of a shoe shine is 12 minutes. Assume that service times are exponentially distributed and that the
queuing system model is (M/M/1):(GD/infinity/infinity). Does this queuing system have a steady state?
It cannot be determined.
Yes
none of the other choices
No
An average of 36 customers per hour arrives at a bank branch office (Poisson arrival)
and wait in a single line to be served by the first available teller. The average time for
each teller to service a customer is 4 minutes (exponentially distributed). Each teller
earns $160/day and the bank branch office assesses a waiting cost of $50/day that a
customer waits in the system.
How many tellers should be on duty in this bank branch office to minimize the total
cost of this waiting line system?
2
4
5
Chapter 13 Solutions
Practical Management Science
Ch. 13.3 - Prob. 1PCh. 13.3 - Prob. 2PCh. 13.3 - Prob. 3PCh. 13.3 - Prob. 4PCh. 13.4 - Prob. 5PCh. 13.4 - Prob. 6PCh. 13.4 - Prob. 7PCh. 13.4 - Prob. 8PCh. 13.5 - Prob. 9PCh. 13.5 - Prob. 10P
Ch. 13.5 - Prob. 11PCh. 13.5 - Prob. 12PCh. 13.5 - Prob. 13PCh. 13.5 - Prob. 14PCh. 13.5 - Prob. 15PCh. 13.5 - Prob. 16PCh. 13.5 - Prob. 17PCh. 13.5 - Prob. 18PCh. 13.5 - Prob. 19PCh. 13.5 - Prob. 20PCh. 13.5 - Prob. 21PCh. 13.5 - Prob. 22PCh. 13.5 - Prob. 23PCh. 13.5 - Prob. 24PCh. 13.5 - Prob. 25PCh. 13.5 - Prob. 26PCh. 13.5 - Prob. 27PCh. 13.5 - Prob. 28PCh. 13.5 - Prob. 29PCh. 13.5 - Prob. 30PCh. 13.5 - Prob. 31PCh. 13.5 - Prob. 32PCh. 13.5 - Prob. 33PCh. 13.5 - Prob. 34PCh. 13.5 - Prob. 35PCh. 13.5 - Prob. 36PCh. 13.5 - Prob. 37PCh. 13 - Prob. 46PCh. 13 - Prob. 47PCh. 13 - Prob. 48PCh. 13 - Prob. 49PCh. 13 - Prob. 50PCh. 13 - Prob. 51PCh. 13 - Prob. 52PCh. 13 - Prob. 54PCh. 13 - Prob. 58PCh. 13 - Prob. 59P
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, operations-management and related others by exploring similar questions and additional content below.Similar questions
- During nearly four decades of business operations, Memphis-based FedEx has earned a reputation for reliable, on-time delivery of packages to homes and offices around the country. Founder Fred Smith originally focused on overnight deliveries, choosing Memphis as the company’s headquarters because the airport rarely closes due to bad weather. With FedEx’s planes departing and arriving on schedule nearly all the time, its express shipments usually remained on schedule, then and now. To reassure customers that delivery will take place when and where promised, the firm offers a money-back guarantee on time-sensitive express shipments, among other services. FedEx has steadily expanded its portfolio of services since the 1970s. Its original overnight express delivery is currently available to U.S. customers in various forms, including “first-overnight” delivery, next-morning delivery, next-afternoon delivery, and budget-pleasing two- or three-day delivery. The company’s services also include cost-effective ground delivery for parcels and extra-speedy same-day delivery for urgent deliveries within 1,800 cities. Over the years, FedEx has widened its delivery network to more than 220 countries. It has purchased more cargo jets and acquired specialized shipping firms, including Tiger International, Roberts Express, RPS, and TNT Express, to support global growth. For international business customers needing products, parts, or raw materials shipped across countries or continents, the company now offers time-saving services such as commercial freight forwarding and cross-border logistical support. To add the convenience of local drop-off and pickup points for U.S. consumers and small businesses, FedEx acquired the Kinko’s office services company in 2004 and later rebranded it as FedEx Office. This acquisition also added printing and copying to the menu of services offered. Then the company arranged for large U.S. retailers such as Walgreens, Albertsons, Kroger, and Safeway to accept packages for shipment and receive package delivery for customer pickup in thousands of store locations. This means people who want to send a package can head to a nearby retailer and ship where they shop, rather than making a separate trip to the FedEx location. It’s also a safe alternative for packages to be picked up by people who don’t want FedEx shipments left by the front door. Another service FedEx offers to small and mid-sized businesses, including retailers, is FedEx Fulfillment. The purpose is to expedite order fulfillment by having each business store its products in a FedEx warehouse. Then, when the business’s customers place orders, FedEx puts the products into boxes bearing the business’s own logo and ships directly to those customers. The business doesn’t need a separate warehouse or staff for fulfillment, and packages are on their way to customers more quickly because the products were in FedEx’s warehouse, ready to be packed and shipped. This service puts FedEx into direct competition with Amazon.com, which offers a similar service to merchants that sell through the online Amazon Marketplace. But it also gives businesses that don’t sell via Amazon a fast and professional fulfillment alternative. FedEx is careful to let customers know, through media and social-media announcements, when it anticipates that extreme weather or other conditions will cause delays or force it to halt pickups and deliveries. For the duration of Hurricane Irma, for example, FedEx said it would suspend deliveries in Florida. Some Florida customers who had ordered generators to be delivered via FedEx were unhappy, because they worried about being without power during and after the storm. But one FedEx employee loaded several generator orders into his car and took them to customers himself. When a customer posted a grateful compliment to FedEx on Facebook, the message generated thousands of likes, shares, and positive comments. The company also received positive comments for its donations of cash and transportation services to areas devastated by Hurricanes Irma, Harvey, and Maria. According to the American Customer Satisfaction Index (ACSI), FedEx often tops the list of U.S. shipping companies as ranked by customers surveyed. Every day, the company delivers 13 million packages—and during the busy year-end holiday season, it delivers many more. By meeting customers’ expectations for on-time deliveries, FedEx has increased annual revenues beyond $60 billion and positioned itself for continued growth in the future. How does FedEx’s money-back guarantee address customers’ concerns about heterogeneity?arrow_forwardMany of a bank’s customers use its automated banking machine (ABM). During the early eveninghours in the summer months, customers arrive at an ABM at the rate of one every other minute(assume Poisson). Each customer spends an average of 99 seconds completing the transaction.Transaction times are exponentially distributed. Assume that the length of the queue is not aconstraint. Determine the average time customers spend at the machine, including waiting in line and completing transactions. Determine the probability that a customer will not have to wait upon arrival at the ABM. Determine the utilization of the ABM.arrow_forwardAn average of 300 customers per hour arrive at a hugebranch of bank 2. It takes an average of 2 minutes to serveeach customer. It costs $10 per hour to keep open a tellerwindow, and the bank estimates that it will lose $50 infuture profits for each hour that a customer waits in line.How many teller windows should bank 2 open?arrow_forward
- Patients arrive at a dentist’s office with an arrival rate of 2.8 patients per hour. The dentist can treat patients at a service rate of 3 patients per hour. A study of patient waiting times shows that a patient waits an average of 30 minutes before seeing the dentist. Note the M/M/1 model does not necessarily apply here. What are the arrival and service rates in terms of patients per minute? What is the average number of patients in the waiting room? If a patient arrives at 10:10am, at what time is the patient expected to leave the office?arrow_forwardA post office has a single line for customers waiting for the next available postal clerk. There are two postal clerks who work at the same rate. The arrival rate of customers follows a Poisson distribution, while the service time follows an exponential distribution. The average arrival rate is three per minute and the average service rate is two per minute for each of the two clerks. How long does the average person spend waiting for a clerk? 1.143 minutes 3.429 minutes 1.929 minutes 0.643 minutearrow_forwardAutomobiles arrive at the drive-through window at a post office at the rate of 7 every 10 minutes. The average service time is 7 minutes. The Poisson distribution is appropriate for the arrival rate and service times are exponentially distributed.(Note: the given equations are NOT necessarily in the correct order.) What is the average time a car is in the system? What is the average number of cars in the system? What is the average time cars spend waiting to receive service? What is the average number of cars in line behind the customerreceiving service? What is the probability that there are no cars at the window? What percentage of the time is the postal clerk busy? What is the probability that there are exactly two cars in the system?arrow_forward
- Please do not give solution in image formate thanku.arrow_forwardA request for assistance at the reference desk at a library is submittedat an average rate of 9 per hour (Poisson distribution). At the reference desk, there is only one librarianand he can serve customers in 6 minutes on average (exponential distribution). Calculate according tothe queuing model M/M/1:1. Server utilization2. Expected number of customers in queue3. Expected waiting time of customer in queuearrow_forwardA chemical plant stores spare parts for maintenance in a large warehouse. Throughout the working day, maintenance personnel go to the warehouse to pick up supplies needed for their jobs. The warehouse receives a request for supplies, on average, every 2 minutes (Poisson distributed). The average request requires 1.7 minutes to fill (exponential service times). Maintenance employees are paid $20 per hour, and warehouse employees are paid $12 per hour. The warehouse is open 8 hours each day. What is the optimal number of warehouse employees to hire? (Hint: Time spent by maintenance workers waiting in line for supplies should be considered an expense.) What is the total cost per hour (waiting plus warehouse employee labor cost) of your solution?arrow_forward
- For the first five hours of the day, the arrival rate at the book store is 35 customers per hour. The book store is capable of serving 30 customers per hour. Assume that the system is empty at the start and that no customer who arrives leaves without being served. At the end of the first five hours, how many patients would you expect to find in line? customersarrow_forwardFor Billys bank situation in problems 12.4 and 12.5, the salary and benefits for the teller would be 12 dollars per hour. The bank is open 8 hours each day. It has been estimated that the wait time cost is 25$ per hour in line. How many Customers would enter the bank on a typical day? How much total time would the customers spend waiting in line during the entire day if two tellers were used? What is the total Daily waiting cost? How much total time would customers spend waiting in line during the entire day if two tellers were used? What is the total daily waiting cost? If billy wishes to minimize the total waiting time and personal cost how many tellers should be used?arrow_forward(Please do not give solution in image format thanku) A single Automated Teller Machine (ATM) is located on the ground floor of a popular shopping mall. Service time at this machine is exponentially distributed. On average, the ATM machine can serve a customer in 3 minutes. Customer arrivals at the machine are Poisson distributed, with an average of 15 customers an hour. Relevant formulas to analyze this M/M/1 model are available in your textbook. What percent of the time is this machine idle? 25% 0% 75% 50% 100%arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Practical Management ScienceOperations ManagementISBN:9781337406659Author:WINSTON, Wayne L.Publisher:Cengage,
MarketingMarketingISBN:9780357033791Author:Pride, William MPublisher:South Western Educational Publishing
Practical Management Science
Operations Management
ISBN:9781337406659
Author:WINSTON, Wayne L.
Publisher:Cengage,
Marketing
Marketing
ISBN:9780357033791
Author:Pride, William M
Publisher:South Western Educational Publishing