Chapter 8 Test Questions
8.4.1 A mail order firm has a total of 12 Watts lines coming into the customer service
department (CSD), which has five customer service representatives. On average, two
potential customers call CSD every minute. Each customer service representative
requires on average 2 minutes to serve a customer. On one of the days two of the Watts
lines happen to be down (as a result only 10 Watts lines are available that day). As a
result, the mail order firm can expect that
(a) The proportion of potential customers getting a busy signal will
(i) Increase
(ii) Decrease
(iii) Remained unchanged
(b) The average waiting time that customers experience will
(i) Increase
(ii) Decrease
(iii) Remained unchanged
(c) The average utilization of customer service representatives will
(i) Increase
(ii) Decrease
(iii) Remained unchanged.
Answers:
8.4.2 A manufacturer of auto parts has just learnt about the Toyota production system and is
trying to implement JIT. Traditionally there has been no control on the amount of work in
process inventory between stages (it has been known to exceed 500 parts between some
stages). As a first step the amount of work in process inventory between stages is limited to
a maximum of 20 parts. What, if any, impact does this have on the output from the factory
on the short term?
8.4.3 A mail order company has one department taking customer orders and the other handling
customer complaints. Currently each department has a separate telephone number. Each
department has 7 Watts lines served by two customer service representatives. Calls come
into each department at the rate of 1 per minute. Each customer service representative
takes on average 1.5 minutes to serve a customer. A proposal has been put forward to
merge the to departments and cross train the workers. The new department would, as a
result, have 14 watts lines served by four customer service representatives. As the
operations manager, you know that
(a) The proportion of callers getting a busy signal will
(i) Increase
(ii) Decrease
(iii) Remained unchanged.
(b) The average utilization of customer service representatives will
(i) Increase
(ii) Decrease
(iii) Remained unchanged
Answers:
8.4.4 Star Brite Media (SBM), an independent video rental store, carries digital projection
systems that customers can rent out together with new, high-definition DVDs. The store
manager is forecasting that, in an average week, about 21 customers would ask to rent a
projection system, the exact number of requests per week being random and may be
assumed to be Poisson distributed. Their projection rental time is estimated to follow
exponential distribution with a mean of about 3 days. (SBM is open 7 days per week.)
a. What is the minimum number of projection systems Sandra should buy to ensure a
service level of 90%, i.e., that the probability that a projection system is available when a
customer requests to rent one is about 90%? (Assume that customers who are interested
in renting a projection system but do not find one available do not wait, but go to find one
at another store.)
b. Instead of buying outright, SBM has the option of leasing the projection systems at a
special rate of $199 per month per projection system. (This includes insurance on the
systems.) What is the break-even price that SBM should charge per day for renting out a
projection system? (Assume 30 days per month, an average rental length of 3 days, and a
service level of 90%.)
8.4.5 Jasper Valley Motors (JVM) is a mid-sized, family-run auto repair shop. To assure customer
vehicles are being serviced. In an average week, 15.5 major repairs are scheduled for which
owners request a loaner car (the service department is open five days per week). Of course, the
exact number of loaner requests is random, and the time between requests may be assumed to be
policy is to take $50 off the cost of the service as compensation for the customer inconvenience,
as they must find alternate transportation to and from the shop. Most repairs are done within a
day but some take longer, requiring the customer to keep the loaner car for several days. It has
been observed that on average, a customer keeps a loaner car for 1.2 days, and the actual time
may be assumed to be exponentially distributed.
a. What is the probability that a customer who requests a loaner car from JVM will actually
get one?
b.
e., not loaned out to customers)?
c Suppose JVM leases the loaner cars from an automaker at a rate of $350 per month per
the cost of the necessary paperwork when the car goes out as well as cleaning the car
ner car program
(including discounts to those who do not receive loaners)? Assume 20 days in a month.
8.4.6 According to the Wall St Journal, research has shown that women take about twice as
long in public restrooms as men (roughly, 3 minutes to 1.4 minutes). It is therefore not
a consequence, many states have passed so-called Potty Parity Laws. (A Google search
lengths for restrooms at public facilities such as theaters and convention halls. Laws in
Maryland and New York mandate an equal number of toilets for men and women (older
women. For example, California requires a 4 to 1 ratio.
a. Assuming that a typical facility serves an equal number of men and women, would you expect the
Maryland and New York legislation to be adequate in delivering equal waiting lines? Why?
b. The Colorado Convention Center in Denver has dealt with potty parity by installing movable
room is
gets up to 75% of capacity. What are the benefits of this approach? How does it compare
to supply chain management techniques we discussed in class
8.4.7 Mateo is COO of the company We-Do-Your-Taxes (WDYT). WDYT typically prepares
taxes for physicians in three steps: step 1 involves a customer service representative
(CSR) talking with a customer physician and receiving all relevant financial information
(pay stubs, expenses, etc.); in step 2 another employee takes all the data from the CSR
and fills out all relevant tax statements. Finally, in step 3, a third employee compiles all
tax statements, and does a final quality check for completeness and mails out the tax
statements to the governmental agency (the IRS) and a copy to the customer.
Mat -point-of-
and filing.
a. What are the benefit(s) and disadvantage(s) of the single-point-of-contact process and why?
Benefits:
Disadvantages:
We are going against Adam Smith: generalists typically will lose specialization benefits,
resulting in service times that exceed the sum of service times of specialists
b.
a more diversified clientele. Under Plan G, WDYT would also serve other professionals,
including small business owners, in addition to the current customer base of physicians.
Under Plan G, Mateo would authorize more hiring and expand capacity proportional to
the increase in business (in terms of number of taxes prepared per month). How would
Plan G impact the quality of service in terms of responsiveness ?