USC Marshall School of Business
BUAD 311 Operations Management
Fall 2022
Quiz 1 Preparation Questions
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Quizzes are meant to help keep you on track with the course material. You are free to
work in groups on these questions (and encouraged to do so), but you cannot ask
the peer tutors, TA, or instructors for help with them.
Only the final answers are provided here. You are responsible for developing the steps
towards the final answers.
On the day of the quiz in class, one of the following preparation questions will be
randomly selected, with slightly different numbers and small modifications including a
new subquestion.
Round your final answers to two decimal points.
1. There is a new coffee shop on campus, and the owner comes to you for help with
analyzing its operational process. For simplicity, we only focus on the most popular
drink, latte, in our analysis and assume that each order contains 1 latte. For each
order, it takes 2 minutes for a cashier to confirm the order and take the payment,
3 minutes for a barista to make the espresso and 2 minutes to steam the milk, and
lastly, 1 minute for a worker to pack and deliver the latte. Currently, the coffee
shop has 1 cashier for taking orders, 2 baristas for making latte and 1 worker for
packing and delivering the drinks.
a) What is the process capacity for this coffee shop?
The process capacity is 24 orders/hour.
b) If the demand rate is 10 orders/hour, what is the utilization rate of the 2 baristas?
The utilization rate of the 2 baristas is 41.67%.
c) If the 2 baristas and the worker for packing and delivering are cross-trained, what
will be the new process capacity?
The new process capacity is 30 orders/hour.
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USC Marshall School of Business
BUAD 311 Operations Management
Fall 2022
d) (Ignore the cross-training part.) The espresso machine breaks down once every 2
hours, and it takes 12 minutes to repair it before the baristas can make latte again.
After taking this into account, what is the process capacity for the coffee shop?
The process capacity is 21.82 orders/hour.
2. Patients visiting the emergency department of the SUC Verdugo hospital are classified
as two groups; Group 1 are those who are treated by a nurse and group 2 are those
who are in more severe condition and are seen by a doctor. Below is the flow diagram
of the process. Both groups are first admitted by the front desk. Then a nurse visit
measures the patient’s vital signs. Next, if the patient is seen by another nurse (if in
group 1), or by a doctor (if in group 2). All patients then go to discharge step where
they are instructed by another nurse regarding the follow-ups. There are two (2) staffs
available at the front desk, three (3) nurses available for measuring vital signs, two
(2) nurses available for group1 patients and two (2) doctors available for group 2
patients. Also, there are three (3) staffs at the discharge stage.
Nurse visit
(group 1)
Front
Desk
Discharge
instruction
Vital
signs
Doctor visit
(group 2)
Group 1
Group 2
We observe the following activity times at each station:
Station
Front Desk
Vital Signs
Nurse visit
Doctor visit
Discharge
Completion Time in Minutes
10
7
15
25
10
a. What is the flow time for a patient in group 1?
42 minutes.
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USC Marshall School of Business
BUAD 311 Operations Management
Fall 2022
b. What is the flow time for a patient in group 2?
52 minutes.
c. Suppose that every hour on average 10 patients show up (classified as group 1)
and 5 patient show up (classified as group 2). What is the implied utilization of
each of the five stations?
Front Desk:
Vital Signs station:
Nurses station:
Doctors station:
Discharge station:
125%
58.33%
125%
104.17%
83.33%
d. What is the bottleneck station? Explain your answer
Both Front Desk and Nurses Station are bottleneck as they have the highest
implied utilization.
e. What is the capacity of the emergency department?
12 patients per hour.
3. You are managing one of the Tandoor-India’s restaurant. All the table are walk-in
(no reservation can be made in advance). Customers that arrive and request a table
are divided as follows: 50% require a table of size two, 40% require a table of size
four, and 10% request a table of size six. The average waiting times for each type
of table is given as:
Table type
Table for two
Table for four
Table for six
Waiting time
10 minutes
30 minutes
40 minutes
The number of parties waiting for a table for two is on average 2.
Hint: This question is on the Little’s law.
a) What is the arrival rate of parties requesting of size two per hour?
12 parties per hour.
b) What is the total arrival rate of parties requesting tables (of any size) per hour?
24 parties/hr.
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USC Marshall School of Business
BUAD 311 Operations Management
Fall 2022
c) What is the average number of parties requesting table of size four per hour?
9.6 parties/hr.
d) What is the average number of parties waiting for a table for four?
4.8 parties.
4. H&R Block is a tax preparation company. Based on the complexity of clients’ tax
situation they classify the clients into three groups. The data from previous years
shows that on average this company has the following demand mix: Group 1 (30% of
cases), Group 2 (15% of cases), Group 3 (55% of cases). In order to prepare the
income tax statements, H&R Block needs to go through several activities, and the
processing time of each activity varies for different groups. The following table
summarizes this information (all numbers are expresses in minutes per case):
Group
Filing Time
1
2
3
20
30
40
Initial meeting
Time
30
90
0
Preparation
Time
70
100
200
Review
Time
20
30
5
The activities are performed by four persons:
• Robert, who is in charge of “Filing”
• Daniela and Mary, who are in charge of “Initial meeting and Review”. These two
persons are cross-trained and work at the same speed.
• Sam, who is in charge of “Preparation”
Suppose that all four persons work eight hours per day and 25 days a month. Suppose
that there are 50 cases (in total in all three groups) each month.
a) What is the implied utilization of Robert?
13.54%
b) What is the implied utilization of Mary?
7.45%
c) What is the implied utilization of Sam?
60.83%
d) Which resource is the bottleneck? Explain your answer.
Sam is the bottleneck because he has the highest implied utilization.
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