Operations and Supply Chain Management The Core

INVENTORY MANAGEMENT chapter 11 389
Because customers generally do not wait for tires but go elsewhere, you decide on
a service probability of 98 percent. Assume the demand occurs 365 days per year.
a. Determine the order quantity.
b. Determine the reorder point.
31. UA Hamburger Hamlet (UAHH) places a daily order for its high-volume items
(hamburger patties, buns, milk, and so on). UAHH counts its current inventory
on-hand once per day and phones in its order for delivery 24 hours later.
Determine the number of hamburgers UAHH should order for the following
conditions:
Average daily demand 600
Standard deviation of demand 100
Desired service probability 99%
Hamburger inventory 800
32. A local service station is open 7 days per week, 365 days per year. Sales of
10W40 grade premium oil average 20 cans per day. Inventory holding costs are
$0.50 per can per year. Ordering costs are $10 per order. Lead time is two weeks.
Backorders are not practical—the motorist drives away.
a. Based on these data, choose the appropriate inventory model and calculate the
economic order quantity and reorder point. Describe in a sentence how the
plan would work. Hint: Assume demand is deterministic.
b. The boss is concerned about this model because demand really varies. The
standard deviation of demand was determined from a data sample to be 6.15
cans per day. The manager wants a 99.5 percent service probability. Determine
a new inventory plan based on this information and the data in part (a). Use
Q opt from part (a).
33. Dave’s Auto Supply custom mixes paint for its customers. The shop performs a
weekly inventory count of the main colors used for mixing paint. Determine the
amount of white paint that should be ordered using the following information:
Average weekly demand
20 gallons
Standard deviation of demand 5 gallons/week
Desired service probability 98%
Current inventory
25 gallons
Lead time
1 week
34. SY Manufacturers (SYM) is producing T-shirts in three colors: red, blue, and
white. The monthly demand for each color is 3,000 units. Each shirt requires
0.5 pound of raw cotton that is imported from Luft-Geshfet-Textile (LGT)
Company in Brazil. The purchasing price per pound is $2.50 (paid only when
the cotton arrives at SYM’s facilities) and transportation cost by sea is $0.20 per
pound. The traveling time from LGT’s facility in Brazil to the SYM facility in the
United States is two weeks. The cost of placing a cotton order, by SYM, is $100
and the annual interest rate that SYM is facing is 20 percent.
a. What is the optimal order quantity of cotton?
b. How frequently should the company order cotton?
c. Assuming that the first order is needed on April 1, when should SYM place
the order?
d. How many orders will SYM place during the next year?
e. What is the resulting annual holding cost?
f. What is the resulting annual ordering cost?
g. If the annual interest cost is only 5 percent, how will it affect the annual
number of orders, the optimal batch size, and the average inventory? (You are
not expected to provide a numerical answer to this question. Just describe the
direction of the change and explain your answer.)