All Matches

Solution Library

Expert Answer

Textbooks

Search Textbook questions, tutors and Books

Oops, something went wrong!

Change your search query and then try again

Result Not Found

Books FREE
Tutors
Study Help
Hire a Tutor
AI Study Help New

Search
Sign In
Register

study help
business
practical management science

Questions and Answers of Practical Management Science

In Example 14.4 of Section 14.5, we examined whether an MM1 system with a single fast server is better or worse than an MMs system with several slow servers. Keeping the same inputs as in the
Make any assumptions about the warm-up time and runtime you believe are appropriate. Try solving the problem with exponentially distributed copying times. Then try it with gamma-distributed copying
Simulate the system in Problem
Given the model in the Multiserver Simulation.xlsm file, what unit cost parameters should be used if we are interested in “optimizing” the system? Choose representative inputs and unit costs, and
How long does it take to reach steady state? Use simulation, with the Multiserver Simulation.xlsm file, to experiment with the effect of warm-up time and runtime on the key outputs. For each of the
Use exponentially distributed service times and a warm-up period of 1 hour for each.d. Why might the use of a long warm-up time bias the results toward worse system behavior than would actually be
The Smalltown Credit Union experiences its greatest congestion on paydays from 11:30 A.M. until 1:00 P.M.During these rush periods, customers arrive according to a Poisson process at rate 2.1 per
Using the arrival rates from the lunchtime rush example, it seems sensible to vary the number of servers so that more servers work during the busy hours. In particular, suppose management wants to
Note that the sum of these rates is the same as the sum of the rates in the example, so that we expect the same total number of arrivals, but now they are more concentrated in the noon to 1 P.M.
In the lunchtime rush example, the arrival rate changed fairly gradually throughout the period of interest.Assume now that the arrival rate first increases and then decreases in a more abrupt manner.
In the lunchtime rush example, we assumed that the system starts empty and idle at 11 A.M. Assume now that the restaurant opens earlier than 11 A.M., but we are still interested only in the period
The small mail-order firm Sea’s Beginning has one phone line. An average of 60 people per hour call in orders, and it takes an average of 1 minute to handle a call. Time between calls and time to
Two one-barber shops sit side by side in Dunkirk Square. Each shop can hold a maximum of 4 people, and any potential customer who finds a shop full will not wait for a haircut. Barber 1 charges $11
Consider the following two queueing systems.■ System 1: An MM1 system with arrival rate and service rate 3μ■ System 2: An MM3 system with arrival rate and each server working at rate
On average, 100 customers arrive per hour at Gotham City Bank. It takes a teller an average of 2 minutes to serve a customer. Interarrival and service times are exponentially distributed. The bank
The manager of a bank wants to use an MMs queueing model to weigh the costs of extra tellers against the cost of having customers wait in line. The arrival rate is 60 customers per hour, and the
Referring to Problem 18, suppose the airline wants to determine how many checkpoints to operate to minimize operating costs and delay costs over a 10-year period. Assume that the cost of delaying a
For the MM1 queueing model, why do the following results hold? (Hint: Remember that 1 is the mean service time. Then think how long a typical arrival must wait in the system or in the queue.)a. W
A worker at the State Unemployment Office is responsible for processing a company’s forms when it opens for business. The worker can process an average of four forms per week. In 2006, an average
A bank is trying to determine which of two machines to rent for check processing. Machine 1 rents for$10,000 per year and processes 1000 checks per hour.Machine 2 rents for $15,000 per year and
Consider an airport where taxis and customers arrive(exponential interarrival times) with respective rates of 1 and 2 per minute. No matter how many other taxis are present, a taxi will wait. If an
The limited source model can often be used to approximate the behavior of a computer’s CPU ( central processing unit). Suppose that 20 terminals (assumed to always be busy) feed the CPU. After the
A laundromat has 5 washing machines. A typical machine breaks down once every five days. A repairman can repair a machine in an average of 2.5 days.Currently, three repairmen are on duty. The owner
On average, 40 cars per hour are tempted to use the drive-through window at the Hot Dog King Restaurant.(We assume that interarrival times are exponentially distributed.) If a total of more than four
A service facility consists of 1 server who can serve an average of 2 customers per hour (service times are exponential).An average of 3 customers per hour arrive at the facility (interarrival times
On average, 100 customers arrive per hour at the Gotham City Bank. The average service time for each customer is 1 minute. Service times and interarrival times are exponentially distributed. The
MacBurger’s is attempting to determine how many servers to have available during the breakfast shift. On average, 100 customers arrive per hour at the restaurant.Each server can handle an average
In this problem, all interarrival and service times are exponentially distributed.a. At present, the finance department and the marketing department each has its own typists. Each typist can type 25
A small bank is trying to determine how many tellers to employ. The total cost of employing a teller is $100 per day, and a teller can serve an average of 60 customers per day. On average, 50
A supermarket is trying to decide how many cash registers to keep open. Suppose an average of 18 customers arrive each hour, and the average checkout time for a customer is 4 minutes. Interarrival
Each airline passenger and his luggage must be checked to determine whether he is carrying weapons onto the airplane. Suppose that at Gotham City Airport, 10 passengers per minute arrive, on
Expand the MMs Template.xlsm file so that the steadystate probability distribution of the number in the system is shown in tabular form and graphically. That is, enter values 0, 1, and so on (up to
In the MMs model, where μ is the service rate per server, explain why μ is not the appropriate condition for steady state, but sμ is.
If you average these, what parameter of the MMs model are you estimating?Use these numbers to estimate the arrival rate .If instead these numbers were observed service times, what would their
Suppose that you observe a sequence of interarrival times, such as 1.2, 3.7, 4.2, 0.5, 8.2, 3.1, 1.7, 4.2, 0.7, 0.3, and 2.0. For example, 4.2 is the time between the arrivals of customers 2 and
For an MM1 queueing system, we know that L (μ ). Suppose that and μ are both doubled.How does L change? How does W change? How does WQ change? How does LQ change? (Remember the basic
Expand the MM1 Template.xlsx file so that the steady-state probability distribution of the number in the system is shown in tabular form and graphically.That is, enter values 0, 1, and so on (up to
The MM1 Template.xlsx file is now set up so that when you enter any time value in cell H11, the formula in cell I11 gives the probability that the wait in queue will be greater than this amount of
The MM1 Template.xlsx file is now set up so that you can enter any integer in cell E11 and the corresponding probability of that many in the system appears in cell F11. Change this setup so that
The Decision Sciences Department is trying to determine whether to rent a slow or a fast copier. The department believes that an employee’s time is worth$15 per hour. The slow copier rents for $4
A fast-food restaurant has one drive-through window.On average, 40 customers arrive per hour at the window. It takes an average of 1 minute to serve a customer. Assume that interarrival and service
Consider a fast-food restaurant where customers enter at a rate of 75 per hour, and 3 servers are working.Customers wait in a single line and go, in FCFS fashion, to the first of the 3 servers who is
Consider a bank where potential customers arrive at rate of 60 customers per hour. However, because of limited space, 1 out of every 4 arriving customers finds the bank full and leaves immediately
Little’s formula applies to an entire queueing system or to a subsystem of a larger system. For example, consider a single-server system composed of two subsystems.The first subsystem is the
Assume that parts arrive at a machining center at a rate of 60 parts per hour. The machining center is capable of processing 75 parts per hour—that is, the mean time to machine a part is 0.8
This estimates the probability P(X 1). Now find all random numbers that are greater than 4.Among these, find the fraction that are greater than 5.This estimates the probability P(X 4 1|X
Do exponentially distributed random numbers have the memoryless property? Here is one way to find out.Generate many exponentially distributed random numbers with mean 3, using the formula in the
Does the histogram have the shape you would expect?d. Suppose you collected the data in column A by timing arrivals at a store. The value in cell A4 is the time (in minutes) until the first arrival,
We can easily generate random numbers in a spreadsheet that have an exponential distribution with a given mean. For example, to generate 200 such numbers from an exponential distribution with
Explain the basic relationship between the exponential distribution and a Poisson process. Also, explain how the exponential distribution and the Poisson distribution are fundamentally different.
An extremely important concept in queueing models is the difference between rates and times. If represents a rate (customers per hour, say), then argue why 1 is a time and vice versa.
Austin (1977) conducted an extensive inventory analysis for the United States Air Force. He found that for over 250,000 items the annual holding cost was assumed to equal 32% of the item’s purchase
Based on Brout (1981). Planner’s Peanuts sells 100 products. The company has been disappointed with the high level of inventory it keeps of each product and its low service level (percentage of
A computer manufacturer produces computers for 40 different stores. To monitor its inventory policies, the manufacturer needs to estimate the mean and standard deviation of its weekly demand. How
A trucking firm must decide at the beginning of the year on the size of its trucking fleet. If on a given day the firm does not have enough trucks, the firm will have to rent trucks from Hertz.
A highly perishable drug spoils after 3 days. A hospital estimates that it is equally likely to need between 1 and 9 units of the drug daily. Each time an order for the drug is placed, a fixed cost
Work the previous problem when the demands are positively correlated, as they might be with products such as peanut butter and jelly. Now use 0.3, 0.5, and 0.7 in your simulations.
The unit cost of each product is$7.50, the unit price for each product is $10, and the unit refund for any unit of either product not sold is$2.50. The company must decide how many units of each
The correlation between D1 and D2 is , where is a negative number between 1 and
These demands are normally distributed with means 1000 and 1200 and standard deviations 250 and
In most of the Walton Bookstore examples in Chapter 11, we assumed that there is a single product.Suppose instead that a company sells two competing products. Sales of either product tend to take
A company currently has two warehouses. Each warehouse services half the company’s demand, and the annual demand serviced by each warehouse is normally distributed with mean 10,000 and standard
An exchange curve can be used to display the tradeoffs between the average investment in inventory and the annual ordering cost. To illustrate the usefulness of a trade-off curve, suppose that a
A company inventories two items. The relevant data are shown in the file P13_65.xlsx. Determine the optimal inventory policy if no shortages are allowed and if the average investment in inventory is
Based on Riccio et al. (1986). The borough of Staten Island has two sanitation districts. In district 1, street litter piles up at an average rate of 2000 tons per week, and in district 2, it piles
A firm knows that the price of the product it is ordering is going to increase permanently by X dollars. It wants to know how much of the product it should order before the price increase goes into
A newspaper has 500,000 subscribers who pay $4 per month for the paper. It costs the company $200,000 to bill all its customers. Assume that the company can earn interest at a rate of 20% per year on
The penalty cost p used in the shortage model might be very difficult to estimate. Instead, a company might use a service-level constraint, such as, “95% of all demand must be met from on-hand
Suppose that instead of measuring shortage in terms of cost per shortage per year, a cost of P dollars is incurred for each unit the firm is short. This cost does not depend on the length of time
In the previous problem, suppose that the cost per order is $1, and the monthly demand is 50 thermometers.What is the optimal order quantity? What is the smallest discount the supplier could offer
A hospital orders its thermometers from a hospital supply firm. The cost per thermometer depends on the order quantity Q, as shown in the file P13_58.xlsx.The annual holding cost is 25% of the
During each year, CSL Computer Company needs to train 27 service representatives. It costs $12,000 to run a training program, regardless of the number of students being trained. Service reps earn a
A drugstore sells 30 bottles of antibiotics per week.Each time it orders antibiotics, there is a fixed ordering cost of $10 and a cost of $10 per bottle. Assume that the store’s cost of capital is
In terms of K, D, and h, what is the average length of time that an item spends in inventory before being used to meet demand? Explain how this result can be used to characterize a fast-moving or
Suppose that instead of ordering the amount Q specified by the EOQ formula, we use the order quantity 0.8Q. Show that the sum of the annual ordering cost and the annual holding cost increases by 2.5%.
Based on Ignall and Kolesar (1972). Father Dominic’s Pizza Parlor receives 30 calls per hour for delivery of pizza. It costs Father Dominic’s $10 to send out a truck to deliver pizzas. Each
Each time an order is placed, costs of $600 per order and $1500 per computer are incurred. Computers are sold for $2800, and if Computco does not have a computer in stock, the customer will buy a
Computco sells personal computers. The demand for its computers during a month follows a normal distribution, with a mean of 400 and standard deviation of
Assume that the cost of holding a TV in inventory for a year is $100. Assume that Lowland begins with 500 TVs in inventory, the cost of a shortage is $150, and the cost of placing an order is $500.a.
Lowland Appliance replenishes its stock of color TVs three times a year. Each order takes 1/9 of a year to arrive. Annual demand for the color TVs follows a normal distribution with a mean of 990 and
Every 4 years, Blockbuster Publishers revises its textbooks.It has been 3 years since the best-selling book The Joy of Excel has been revised. At present, 2000 copies of the book are in stock, and
A department store is trying to decide how many JP Desksquirt II printers to order. Because JP is about to come out with a new model in a few months, the store will order only a limited number of
A firm experiences demand with a mean of 100 units per day. Lead time demand is normally distributed with mean 1000 units and standard deviation 200 units. It costs $6 to hold 1 unit for 1 year. If
A hospital orders its blood from a regional blood bank.Each year, the hospital uses an average of 1040 pints of type O blood. Each order placed with the regional blood bank incurs a cost of $250. The
How do your answers to part a of the previous problem change if, instead of incurring a $40 penalty cost for each shortage, the store has a service level requirement of meeting 95% of all customer
In the previous problem, assume that it costs $300 to place an order. The holding cost per DVD player held in inventory per year is $15. The cost each time a customer orders a DVD player that is not
When the store orders these DVD players from its supplier, it takes an amount of time L for the order to arrive, where L is measured as a fraction of a year. In each of the following, find the mean
Suppose the annual demand for Soni DVD players at an appliance store is normally distributed with mean 150 and standard deviation
That is, the lead time would then be a certain 3 weeks. What is the most it would be willing to pay (and still meet the service level in part a)?
Chicago’s Treadway Tires Dealer must order tires from its national warehouse. It costs $10,000 to place an order. Annual tire sales are normally distributed with mean 20,000 and standard deviation
A hospital must order the drug Porapill from Daisy Drug Company. It costs $500 to place an order. Annual demand for the drug is normally distributed with mean 10,000 and standard deviation 3000, and
A camera store sells an average of 100 cameras per month. The cost of holding a camera in inventory for a year is 30% of the price the camera shop pays for the camera. It costs $120 each time the
Customers at Joe’s Office Supply Store demand an average of 6000 desks per year. Each time an order is placed, an ordering cost of $300 is incurred. The annual holding cost for a single desk is 25%
It costs $5 to store a unit of either product for a year. The cost of placing an order for either product separately or both products together is $100. Software EG’s annual cost of capital is 14%.
The unit purchasing cost is $30 per unit of product 1 and $25 per unit of product
Software EG, a retail company, orders two kinds of software from TeleHard Software. Annually, Software EG sells 800 units of product 1 and 400 units of product
Chicago Mercy Hospital needs to order drugs that are used to treat heart attack victims. Annually, 500 units of drug 1 and 800 units of drug 2 are used. The unit purchasing cost for drug 1 is $150
The particular logarithmic function proposed in Example 13.4 is just one possibility for the cost of a setup cost reduction. In the previous problem, suppose instead that Machey’s has only three
Reconsider Example 13.1. Each time Machey’s orders cameras, it incurs a $125 ordering cost. Assume that Machey’s could make an investment to decrease this ordering cost. Suppose that any 10%
A luxury car dealer must pay $20,000 for each car purchased.The annual holding cost is estimated to be 25% of the dollar value of inventory. The dealer sells an average of 500 cars per year. He is

Showing 800 - 900 of 2541

First
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Last

Services

Sitemap
Fun
Definitions
Become Tutor
Study Help Categories
Recent Questions
Expert Questions

Company Info

Security
Copyrights
Privacy Policy
Terms & Conditions
SolutionInn Fee
Scholarship

Get In Touch

About Us
Contact Us
Career
Jobs
FAQ
Campus Ambassador

Secure Payment

Download Our App

© 2024 SolutionInn. All Rights Reserved