Solution Manual
Matching Supply with Demand An Introduction to Operations
Management,
Cachon 5th Edition
,Solution Manual for
Matching Supply with Demand An Introduction to Operations Management, 5th Edition Cachon
Chapter 2-19
Chapter 2
The Process View of the Organization
Q2.1 Dell
The following steps refer directly to Exhibit 2.1.
#1: For 2001, we find in Dell’s 10-k: Inventory = $400 (in million)
#2: For 2001, we find in Dell’s 10-k: COGS = $26,442 (in million)
26,442$ / year
#3: Inventory turns 66.105 turns per year
400$
40% per year
#4: Per unit Inventory cost 0.605% per year
66.105 per year
Q2.2. Airline
We use Little’s law to compute the flow time, since we know both the flow rate as well
as the inventory level:
Flow Time Inventory / Flow Rate 35 passengers / 255 passengers per hour 0.137 hours
8.24 minutes
Q2.3 Inventory Cost
(a) Sales $60,000,000 per year / $2000 per unit 30,000 units sold per year
Inventory $20,000,000/ $1000 per unit 20,000 units in inventory
Flow Time Inventory / Flow Rate 20,000/ 30,000 per year 2/ 3 year 8 months
Turns 1/ Flow Time 1/ (2/ 3 year) 1.5 turns per year
Note: we can also get this number directly by writing: Inventory turns COGS / Inventory
(b) Cost of Inventory: 25% per year /1.5 turns 16.66% . For a $1000 product, this would
make an absolute inventory cost of $166.66 .
Q2.4. Apparel Retailing
(a) Revenue of $100M implies COGS of $50M (because of the 100% markup).
Turns COGS/ Inventory $50M / $5M 10 .
(b) The inventory cost, given 10 turns, is 40%/10 4% . For a 30$ item, the inventory
cost is 0.4 $30 $1.20 per unit .
Q2.5. La Villa
(a) Flow Rate Inventory / Flow Time 1200 skiers /10 days 120 skiers per day
(b) Last year: on any given day, 10% (1 of 10) of skiers are on their first day of skiing
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of
McGraw Hill LLC.
, This year: on any given day, 20% (1 of 5) of skiers are on their first day of skiing
Average amount spent in local restaurants (per skier)
Last year 0.1 $50 0.9 $30 $32
This year 0.2 $50 0.8 $30 $34
% change ($34 $32) / $32 6.25% increase
Q2.6. Highway
We look at 1 mile of highway as our process. Since the speed is 60 miles per hour, it
takes a car 1 minute to travel through the process (flow time).
There are 24 cars on ¼ of a mile, i.e. there are 96 cars on the 1 mile stretch (inventory).
Inventory = Flow Rate * Flow Time: 96 cars = Flow Rate * 1 minute
Thus, the Flow Rate is 96 cars per minute, corresponding to 96*60 = 5760 cars per hour.
Q2.7. Strohrmann Baking
The bread needs to be in the oven for 12 minutes (flow time). We want to produce at a
flow rate of 4000 breads per hour, or 4000/60 = 66.66 breads per minute.
Inventory = Flow Rate * Flow Time: Inventory = 66.66 breads per minute* 12 minutes
Thus, Inventory = 800 breads, which is the required size of the oven.
Q2.8. Mt Kinley Consulting
We have the following information available from the question:
Level Inventory (number of consultants at Flow Time (time spent at that
that level) level)
Associate 200 4 years
Manager 60 6 years
Partner 20 10 years
(a) We can use Little’s law to find the flow rate for associate consultants: Inventory =
Flow Rate * Flow Time; 200 consultants = Flow Rate * 4 years; thus, the flow rate is
50 consultants per year, which need to be recruited to keep the firm in its current size
(note: while there are also 50 consultants leaving the associate level, this says nothing
about how many of them are dismissed vs how many of them are promoted to
Manager level).
(b) We can perform a similar analysis at the manager level, which indicates that the flow
rate there is 10 consultants. In order to have 10 consultants as a flow rate at the
manager level, we need to promote 10 associates to manager level (remember, the
firm is not recruiting to the higher ranks from the outside). Hence, every year, we
dismiss 40 associates and promote 10 associates to the manager level (the odds at that
level are 20%)
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of
McGraw Hill LLC.
, Now, consider the partner level. The flow rate there is 2 consultants per year (obtained
via the same calculations as before). Thus, from the 10 manager cases we evaluate every
year, 8 are dismissed and 2 are promoted to partner (the odds at that level are thereby also
20%).
In order to find the odds of a new hire to become partner, we need to multiply the
promotion probabilities: 0.2*0.2 = 0.04. Thus, a new hire has a 4% chance of making it to
partner.
Q2.9. Major US Retailers
a. Product stays on average for 31.9 days in Costco’s inventory
b. Costco has for a $5 product an inventory cost of $0.1311 which compares to a
$0.2049 at Wal-Mart
Q2.10. McDonald’s
a. Inventory turns for McDonald’s were 92.3. They were 30.05 for Wendy’s.
b. McDonald’s has per unit inventory costs of 0.32%, which for a 3$ meal about
$0.00975 . That compares to 0.998% at Wendy’s where the cost per meal is $0.0299 .
Q2.11. BCH
I = 400 associates, T = 2 years. R I / T 400 associates / 2 yrs 200 associates / yr .
Q2.12. Kroger
Turns R / I 12.3
Matching Supply with Demand: An Introduction to Operations Management
5e
Solutions to Chapter Problems
Chapter 3
Understanding the Supply Process: Evaluating Process Capacity
Q3.1 Process Analysis with One Flow Unit
(a) Capacity of the three resources in units per hour are 60 2 /10 12 , 60 1/ 6 10 ;
60 3 /16 11.25 . The bottleneck is the resource with the lowest capacity, which is
resource 2.
(b) The process capacity is the capacity of the bottleneck, which is 10 units/hr .
(c) If demand 8 units / hr , then the process is demand constrained and the flow rate is
8 units/hr
(d) Utilization = Flow Rate / Capacity . For the three resources they are 8 /12 , 8 /10 , and
8 /11.25 .
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of
McGraw Hill LLC.
Matching Supply with Demand An Introduction to Operations
Management,
Cachon 5th Edition
,Solution Manual for
Matching Supply with Demand An Introduction to Operations Management, 5th Edition Cachon
Chapter 2-19
Chapter 2
The Process View of the Organization
Q2.1 Dell
The following steps refer directly to Exhibit 2.1.
#1: For 2001, we find in Dell’s 10-k: Inventory = $400 (in million)
#2: For 2001, we find in Dell’s 10-k: COGS = $26,442 (in million)
26,442$ / year
#3: Inventory turns 66.105 turns per year
400$
40% per year
#4: Per unit Inventory cost 0.605% per year
66.105 per year
Q2.2. Airline
We use Little’s law to compute the flow time, since we know both the flow rate as well
as the inventory level:
Flow Time Inventory / Flow Rate 35 passengers / 255 passengers per hour 0.137 hours
8.24 minutes
Q2.3 Inventory Cost
(a) Sales $60,000,000 per year / $2000 per unit 30,000 units sold per year
Inventory $20,000,000/ $1000 per unit 20,000 units in inventory
Flow Time Inventory / Flow Rate 20,000/ 30,000 per year 2/ 3 year 8 months
Turns 1/ Flow Time 1/ (2/ 3 year) 1.5 turns per year
Note: we can also get this number directly by writing: Inventory turns COGS / Inventory
(b) Cost of Inventory: 25% per year /1.5 turns 16.66% . For a $1000 product, this would
make an absolute inventory cost of $166.66 .
Q2.4. Apparel Retailing
(a) Revenue of $100M implies COGS of $50M (because of the 100% markup).
Turns COGS/ Inventory $50M / $5M 10 .
(b) The inventory cost, given 10 turns, is 40%/10 4% . For a 30$ item, the inventory
cost is 0.4 $30 $1.20 per unit .
Q2.5. La Villa
(a) Flow Rate Inventory / Flow Time 1200 skiers /10 days 120 skiers per day
(b) Last year: on any given day, 10% (1 of 10) of skiers are on their first day of skiing
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of
McGraw Hill LLC.
, This year: on any given day, 20% (1 of 5) of skiers are on their first day of skiing
Average amount spent in local restaurants (per skier)
Last year 0.1 $50 0.9 $30 $32
This year 0.2 $50 0.8 $30 $34
% change ($34 $32) / $32 6.25% increase
Q2.6. Highway
We look at 1 mile of highway as our process. Since the speed is 60 miles per hour, it
takes a car 1 minute to travel through the process (flow time).
There are 24 cars on ¼ of a mile, i.e. there are 96 cars on the 1 mile stretch (inventory).
Inventory = Flow Rate * Flow Time: 96 cars = Flow Rate * 1 minute
Thus, the Flow Rate is 96 cars per minute, corresponding to 96*60 = 5760 cars per hour.
Q2.7. Strohrmann Baking
The bread needs to be in the oven for 12 minutes (flow time). We want to produce at a
flow rate of 4000 breads per hour, or 4000/60 = 66.66 breads per minute.
Inventory = Flow Rate * Flow Time: Inventory = 66.66 breads per minute* 12 minutes
Thus, Inventory = 800 breads, which is the required size of the oven.
Q2.8. Mt Kinley Consulting
We have the following information available from the question:
Level Inventory (number of consultants at Flow Time (time spent at that
that level) level)
Associate 200 4 years
Manager 60 6 years
Partner 20 10 years
(a) We can use Little’s law to find the flow rate for associate consultants: Inventory =
Flow Rate * Flow Time; 200 consultants = Flow Rate * 4 years; thus, the flow rate is
50 consultants per year, which need to be recruited to keep the firm in its current size
(note: while there are also 50 consultants leaving the associate level, this says nothing
about how many of them are dismissed vs how many of them are promoted to
Manager level).
(b) We can perform a similar analysis at the manager level, which indicates that the flow
rate there is 10 consultants. In order to have 10 consultants as a flow rate at the
manager level, we need to promote 10 associates to manager level (remember, the
firm is not recruiting to the higher ranks from the outside). Hence, every year, we
dismiss 40 associates and promote 10 associates to the manager level (the odds at that
level are 20%)
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of
McGraw Hill LLC.
, Now, consider the partner level. The flow rate there is 2 consultants per year (obtained
via the same calculations as before). Thus, from the 10 manager cases we evaluate every
year, 8 are dismissed and 2 are promoted to partner (the odds at that level are thereby also
20%).
In order to find the odds of a new hire to become partner, we need to multiply the
promotion probabilities: 0.2*0.2 = 0.04. Thus, a new hire has a 4% chance of making it to
partner.
Q2.9. Major US Retailers
a. Product stays on average for 31.9 days in Costco’s inventory
b. Costco has for a $5 product an inventory cost of $0.1311 which compares to a
$0.2049 at Wal-Mart
Q2.10. McDonald’s
a. Inventory turns for McDonald’s were 92.3. They were 30.05 for Wendy’s.
b. McDonald’s has per unit inventory costs of 0.32%, which for a 3$ meal about
$0.00975 . That compares to 0.998% at Wendy’s where the cost per meal is $0.0299 .
Q2.11. BCH
I = 400 associates, T = 2 years. R I / T 400 associates / 2 yrs 200 associates / yr .
Q2.12. Kroger
Turns R / I 12.3
Matching Supply with Demand: An Introduction to Operations Management
5e
Solutions to Chapter Problems
Chapter 3
Understanding the Supply Process: Evaluating Process Capacity
Q3.1 Process Analysis with One Flow Unit
(a) Capacity of the three resources in units per hour are 60 2 /10 12 , 60 1/ 6 10 ;
60 3 /16 11.25 . The bottleneck is the resource with the lowest capacity, which is
resource 2.
(b) The process capacity is the capacity of the bottleneck, which is 10 units/hr .
(c) If demand 8 units / hr , then the process is demand constrained and the flow rate is
8 units/hr
(d) Utilization = Flow Rate / Capacity . For the three resources they are 8 /12 , 8 /10 , and
8 /11.25 .
© McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of
McGraw Hill LLC.
