Practice Questions: Process Analysis and Capacity Management

Practice Questions: Process Analysis and Capacity Management

1.                  The Avis Company is a car rental company and is located 3 miles from the Los Angeles airport (LAX).  Avis is dispatching a bus from its offices to the airport every 2 min.  The average traveling time (a round trip) is 20 min. 

a.       How many Avis buses are traveling to and from the airport?

b.      The branch manager wants to improve the service and suggests dispatching buses every 0.5 min.  She argues that this will reduce the average traveling time from the airport to Avis offices to 2.5 min.  Is she correct?  If your answer is negative then what will the average traveling time be?

2.                  Safety regulations require that the time between airplane takeoffs (on the same runway) will be at least 3 min.  When taking off, the run time of an airplane on the runway is 45 sec.  Planes are on average waiting 4 min and 15 sec for take-off.  On average there are 15 plans taking off per hour. 

a.       How many planes are either on the runway or waiting to take off?

3.                  In Children’s Hospital in Seattle there are on average 60 births per week.  Mother and child stay, on average, two days before they leave the hospital.  In Swedish hospital (also in Seattle), the average number of births per week is 210.  Mothers and children stay in the hospital 2 days on average.

a.       How many new mothers are staying in Children’s Hospital?

b.      How many new mothers are staying in the Swedish Hospital?

c.       The directors of the two hospitals are negotiating unifying the children wards of the two hospitals.  They believe that by doing so they will be able to reduce the number of new mothers staying in the hospital. 

Are they correct?  How many new mothers will stay, on average, in the unified ward?

You may assume that the average number of births and the length of stay of the new mothers will not change.

4.                  The manufacturer of TV sets observed that the higher the work in process the higher the throughput rate, perhaps because when operators see a lot of WIP they work faster.  He also noticed that the relationship between WIP and Throughput rate is:

Throughput rate (units per month) = 10,000 + 0.1WIP

The CEO of the TV Company knows that it is very important to have high through put rate and he wants to achieve a through put rate of 20,000 units per month.  At the same time the CEO knows that long throughput time have a negative impact on the performance of the company.  He instructed the vice president for Operation to reduce the throughput time to one month without changing the throughput rate.  When the company failed to achieve this goal the vice president for operation was fired.

Can the firing of the vice president be justified?  Explain your answer.

5.                  In the last university senate meeting the faculty representative complained about shortage of space in the faculty club.  The representative claimed that a large fraction of the faculty has to wait a long time, sometimes more that 30 min, till a table is available.

At present the faculty club can seat 100 customers.  A study conducted lately found that during lunch time the arrival rate is 150 customers per hour.  Also, the study found that, on average, a person spends in the club, after he/she is seated, 75 min.

a.       If the management of the club wants to satisfy the faculty what should the capacity of the club be?

b.      Club management is short of resources and is unable to add new capacity.  The club management suggests introducing a self service system.  They believe that the new service will result in the faculty staying in the club for only 40 min.  Will the self service system solve the problem?

6.                  Campus Credit Union has 5 representatives, 2 of them specialized in business customers and 3 of them specialized in personal customers. On average, each business customer takes 15 minutes, and each personal customer takes 12 minutes to finish the service. During the 4-5pm rush hour, 10 business customers and 10 personal customers show up.

1. 1. Does the Credit Union have enough capacity during the rush hour?
   2. If the Credit Union cross-trains the representatives so that all of them can handle both the business and personal customers, does the Credit Union have enough capacity during the rush hour?
   3. The Credit Union is unable to cross-train all representatives, but can cross-train one of the representatives originally specialized in business customers. Should the Credit Union pursue this opportunity?

1. 1. The Credit Union is unable to cross-train all representatives, but can cross-train one of the representatives originally specialized in personal customers. Should the Credit Union pursue this opportunity?