,Matching Supply with Demand: An Introduction to Operations Management, 4e (Cachon)
Chapter 2 The Process View of the Organization
1) Butternut is a ski resort in Massachusetts. One of their triple chair lifts unloads 1296 skiers per
hour at the top of the slope. (A triple chair lift can carry three passengers per chair.) The ride
from the bottom to the top takes 5 minutes. How many skiers are riding on the lift at any one
time? (Round the answer to the nearest whole number.)
Answer: 108 skiers
Explanation: Use Little's Law. 1296 skiers/hour * 5/60 = 108 skiers
Difficulty: 3 Hard
Topic: Littles Law
AACSB: Analytical Thinking
Blooms: Apply
2) Home Depot's annual turns are 4.7, its Cost of Goods Sold (COGS) is $44.7 billion, and its
gross margin is 33%. Recall, gross margin = (Revenue – COGS) / Revenue. What is the average
inventory it holds? (Round the answer to 2 decimal places.)
Answer: $9.51 billion
Explanation: $44.7 billion / 4.7 =$9.51 billion. Note that average inventory in dollars is
measured by the cost of goods sold, thus the gross margin does not play a role in the calculation.
Difficulty: 3 Hard
Topic: Littles Law
AACSB: Analytical Thinking
Blooms: Apply
3) A company's holding cost is 16% per year. Its annual inventory turns are 9.5. The company
buys an item for $50. What is the average cost in dollars to hold this item in inventory? (Round
the answer to 2 decimal places.)
Answer: Average cost: $ 0.84
Explanation: The item will be turned 9.5 times a year. Thus, for each turn it stays in inventory,
the holding cost is 16%/9.5 of the cost of the item. Thus, the average cost to hold this item in
inventory is $50 * (16%/9.5) = $0.84
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Apply
1
Copyright 2019 © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior
written consent of McGraw-Hill Education.
,4) Trader Bob, an organic food retail chain, operates 365 days a year. In 2007, the company
turned its inventory approximately 25 times. The company's COGS were 60% of its Sales and its
annual Sales were about $7,000M that year. What was Trader Bob's average inventory in 2007?
(Round the answer to the nearest whole number.)
Answer: $168 million
Explanation: COGS = 0.6 × 7000M = 4200M. Inventory = COGS / Turns = 4200M / 25 =
$168M
Difficulty: 3 Hard
Topic: Littles Law
AACSB: Analytical Thinking
Blooms: Apply
5) Assuming Trader Bob's annual inventory holding costs are 20% (an item that cost $10 to
purchase would cost $2 to hold in inventory for one year), what is the inventory cost of an item
which sells for $20 and costs Trader Bob $12 to buy? Assume that this item has inventory turns
of 25 per year. (Round the answer to 3 decimal places.)
Answer: $0.096
Explanation: 20% per year with 25 turns is .20/25 = 0.008%. COGs is $12. So, inventory cost is
0.008% × $12 = $0.096
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Apply
[The following information applies to questions 6-7.]
Joe's Beer, Bait, & Tackle Co.
Joe's Beer, Bait, & Tackle Co. is a small chain of fishing tackle stores in northern Minnesota. In
2009, the company's revenue was $4,300,000 and its cost of sales was $3,200,000. Assume 52
weeks and 365 days per year.
6) Joe keeps only 5.5 days-of-supply of inventory on average because much of his inventory is
live bait and micro-brew beer, both of which have a short shelf life. What is his annual inventory
turns? (Round the answer to 2 decimal places.)
Answer: 66.36
Explanation: 365/5.5 = 66.36
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Apply
2
Copyright 2019 © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior
written consent of McGraw-Hill Education.
, 7) Given that he has 5.5-days-of-supply of inventory on average, how much inventory does Joe
have on average? (Round the answer to the nearest whole number.)
Answer: $48,219
Explanation: $3,200,000/ (365/5.5) =$48,219
Difficulty: 3 Hard
Topic: Five Reasons to Hold Inventory
AACSB: Analytical Thinking
Blooms: Apply
8) Which of the following best explains why slow turning items may not be profitable at a brick-
and-mortar retailer?
A) If turns are low, days-of-supply will also be low.
B) If turns are low, the gross margin will also be low.
C) If turns are low, the setup costs to stock the shelf will be high.
D) If turns are low, blocking and starving are more likely to occur.
E) If turns are low, units spend a long time on the retailer's shelves.
Answer: E
Explanation: a) If turns are low, days-of-supply will be high. b) it is not necessary that the gross
margin will be low, since various factors affect gross margin. c) setup costs are not affected by
turns. d) starving is less likely to occur when turns are low. e) units spend too much time on the
shelves, and this will increase the inventory holding cost.
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Analyze
9) Is it possible for two firms to have the same annual inventory turns and the same gross-margin
but different days-of-supply?
A) Yes, because days-of-supply measures how long the firm can satisfy demand with its current
inventory whereas inventory turns measures the frequency at which inventory turns over.
B) Yes, inventory turns and gross margin are related but they are independent of days-of-supply
C) Yes, the firm with the higher days-of-supply will have the lower return on invested capital.
D) No, if firms have the same gross-margin then they must have the same days-of-supply.
E) No, if firms have the same inventory turns then they must have the same days-of-supply.
F) None of the above.
Answer: E
Explanation: Knowing inventory turns uniquely specifies days of supply because inventory turns
= 365/ days of supply.
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Analyze
3
Copyright 2019 © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior
written consent of McGraw-Hill Education.
Chapter 2 The Process View of the Organization
1) Butternut is a ski resort in Massachusetts. One of their triple chair lifts unloads 1296 skiers per
hour at the top of the slope. (A triple chair lift can carry three passengers per chair.) The ride
from the bottom to the top takes 5 minutes. How many skiers are riding on the lift at any one
time? (Round the answer to the nearest whole number.)
Answer: 108 skiers
Explanation: Use Little's Law. 1296 skiers/hour * 5/60 = 108 skiers
Difficulty: 3 Hard
Topic: Littles Law
AACSB: Analytical Thinking
Blooms: Apply
2) Home Depot's annual turns are 4.7, its Cost of Goods Sold (COGS) is $44.7 billion, and its
gross margin is 33%. Recall, gross margin = (Revenue – COGS) / Revenue. What is the average
inventory it holds? (Round the answer to 2 decimal places.)
Answer: $9.51 billion
Explanation: $44.7 billion / 4.7 =$9.51 billion. Note that average inventory in dollars is
measured by the cost of goods sold, thus the gross margin does not play a role in the calculation.
Difficulty: 3 Hard
Topic: Littles Law
AACSB: Analytical Thinking
Blooms: Apply
3) A company's holding cost is 16% per year. Its annual inventory turns are 9.5. The company
buys an item for $50. What is the average cost in dollars to hold this item in inventory? (Round
the answer to 2 decimal places.)
Answer: Average cost: $ 0.84
Explanation: The item will be turned 9.5 times a year. Thus, for each turn it stays in inventory,
the holding cost is 16%/9.5 of the cost of the item. Thus, the average cost to hold this item in
inventory is $50 * (16%/9.5) = $0.84
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Apply
1
Copyright 2019 © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior
written consent of McGraw-Hill Education.
,4) Trader Bob, an organic food retail chain, operates 365 days a year. In 2007, the company
turned its inventory approximately 25 times. The company's COGS were 60% of its Sales and its
annual Sales were about $7,000M that year. What was Trader Bob's average inventory in 2007?
(Round the answer to the nearest whole number.)
Answer: $168 million
Explanation: COGS = 0.6 × 7000M = 4200M. Inventory = COGS / Turns = 4200M / 25 =
$168M
Difficulty: 3 Hard
Topic: Littles Law
AACSB: Analytical Thinking
Blooms: Apply
5) Assuming Trader Bob's annual inventory holding costs are 20% (an item that cost $10 to
purchase would cost $2 to hold in inventory for one year), what is the inventory cost of an item
which sells for $20 and costs Trader Bob $12 to buy? Assume that this item has inventory turns
of 25 per year. (Round the answer to 3 decimal places.)
Answer: $0.096
Explanation: 20% per year with 25 turns is .20/25 = 0.008%. COGs is $12. So, inventory cost is
0.008% × $12 = $0.096
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Apply
[The following information applies to questions 6-7.]
Joe's Beer, Bait, & Tackle Co.
Joe's Beer, Bait, & Tackle Co. is a small chain of fishing tackle stores in northern Minnesota. In
2009, the company's revenue was $4,300,000 and its cost of sales was $3,200,000. Assume 52
weeks and 365 days per year.
6) Joe keeps only 5.5 days-of-supply of inventory on average because much of his inventory is
live bait and micro-brew beer, both of which have a short shelf life. What is his annual inventory
turns? (Round the answer to 2 decimal places.)
Answer: 66.36
Explanation: 365/5.5 = 66.36
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Apply
2
Copyright 2019 © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior
written consent of McGraw-Hill Education.
, 7) Given that he has 5.5-days-of-supply of inventory on average, how much inventory does Joe
have on average? (Round the answer to the nearest whole number.)
Answer: $48,219
Explanation: $3,200,000/ (365/5.5) =$48,219
Difficulty: 3 Hard
Topic: Five Reasons to Hold Inventory
AACSB: Analytical Thinking
Blooms: Apply
8) Which of the following best explains why slow turning items may not be profitable at a brick-
and-mortar retailer?
A) If turns are low, days-of-supply will also be low.
B) If turns are low, the gross margin will also be low.
C) If turns are low, the setup costs to stock the shelf will be high.
D) If turns are low, blocking and starving are more likely to occur.
E) If turns are low, units spend a long time on the retailer's shelves.
Answer: E
Explanation: a) If turns are low, days-of-supply will be high. b) it is not necessary that the gross
margin will be low, since various factors affect gross margin. c) setup costs are not affected by
turns. d) starving is less likely to occur when turns are low. e) units spend too much time on the
shelves, and this will increase the inventory holding cost.
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Analyze
9) Is it possible for two firms to have the same annual inventory turns and the same gross-margin
but different days-of-supply?
A) Yes, because days-of-supply measures how long the firm can satisfy demand with its current
inventory whereas inventory turns measures the frequency at which inventory turns over.
B) Yes, inventory turns and gross margin are related but they are independent of days-of-supply
C) Yes, the firm with the higher days-of-supply will have the lower return on invested capital.
D) No, if firms have the same gross-margin then they must have the same days-of-supply.
E) No, if firms have the same inventory turns then they must have the same days-of-supply.
F) None of the above.
Answer: E
Explanation: Knowing inventory turns uniquely specifies days of supply because inventory turns
= 365/ days of supply.
Difficulty: 3 Hard
Topic: Inventory Turns and Inventory Costs
AACSB: Analytical Thinking
Blooms: Analyze
3
Copyright 2019 © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior
written consent of McGraw-Hill Education.
