By: Prof. Y. Peter Chiu

1
Chapter 7 HOMEWORK
By Prof. Y. Peter Chiu
2
7- 4

• The Noname Computer Company builds a
  computer designated modeI ICU2. It imports the
  motherboard of the computer from Taiwan, but the
  company inserts the sockets for the chips and
  boards in its plant in Lubbock, Texas. Each
  computer require a total of 90 64K DRAM (dynamic
  random access memory) chips. Noname sells the
  computers with three add-in boards and two disk
  drives. The company purchases both the DRAM chips
  and the disk drives from an outside supplier. The
  product structure diagram for the ICU2 computer
  is given in Figure 7-6.
• Suppose that the forecasted demands for
  the computer for weeks 6 to 11 are 220, 165, 180,
  120, 75, 300. The starting inventory of assembled
  computers in week 6 will be 75, and the
  production manager anticipates returns of 30 in
  week 8 and 10 in week 10.
• Determine the MPS for the computers.
• Determine the planned order release for the
  motherboards assuming a lot-for-lot scheduling
  rule.
• Determine the scheduling for outside orders for
  the disk drives.

3
7- 5

• For the previous problem, suppose that Noname has
  23,000 DRAM chips in inventory. It anticipates
  receiving a lot of 3,000 chips in week 3 from
  another
• firm that has gone out of business. At the
  current time, Noname purchases the chips from two
  vendors, A and B. A sells the chips for less, but
  will not fill
• an order exceeding 10,000 chips per week.
• If Noname has established a policy of
  inventorying as few chips as possible, what order
  should it be placing with vendors A and B over
  the next six weeks?
• b. Noname has found that not all the DRAM chips
  purchased function properly. From past
  experience it estimates an 8 percent failure rate
  for the chips purchased from vendor A and a 4
  percent failure rate for the chips purchased from
  vendor B.
• What modification in the order scheduling would
  you recommend to compensate for this problem?

4
7-6
Consider the product structure diagram given in
Figure 7-3. Assume that the MPS for the end item
for weeks 10 through 17 is
Week 10 11 12 13
14 15 16 17
Net requirements 100 100 40 40 100
200 200 200

• Assume that lot-for-lot scheduling is used
  throughout. Also assume
• that there is no entering inventory in period 10
  and no scheduling
• receipts.
• Determine the planned order release for component
  A.
• Determine the planned order release for component
  B.
• Determine the planned order release for component
  C. (Hint Note that C is
• required for both A and B.)

5
7-9

• An end item has the product structure given in
  Figure 7-7.
• Write the product structure diagram as an
  indented bill-of-materials list.
• Suppose that the MPS for the end item is

Week 30 31 32 33 34
35
MPS 165 180 300 220 200 240
If production is scheduling on a lot-for-lot
basis, find the planned order release for
component F. c. Using the data in part (b), find
the planned order release for component I. d.
Using the data in part (b), find the planned
order release for component H.
6
7-14

• A single inventory item is ordered from an
  outside supplier. The anticipated demand for this
  item over the next 12 months is 6, 12, 4, 8, 15,
  25, 20, 5, 10, 20 5, 12. Current inventory of
  this item is 4, and ending inventory should be 8.
  Assume a holding cost of 1 per period and a
  setup cost of 40.
• Determine the order policy for this item based
  on
• Silver-Meal.
• Least unit cost.
• Part period balancing.
• Which lot-sizing method resulted in the lowest
  cost for the 12 periods?

7
7-17
The time-phased net requirements for the base
assembly in a table lamp over the next six weeks
are
Week 1 2 3
4 5 6
Requirements 335 200 140 440
300 200

• The setup cost for the construction of the base
  assembly is 200, and the holding cost is 0.30
  per assembly per week.
• a. What lot sizing do you obtain from the EOQ
  formula?
• b. Determine the lot sizes using the Silver-Meal
  heuristic.
• Determine the lot sizes using the Least unit cost
  heuristic.
• d. Determine the lot sizes using Part period
  balancing.
• e. Compare the holding and setup costs obtained
  over the six periods using the policies found in
  parts (a) through (d) with the cost of a
  lot-for-lot police.

8
7-18

• Anticipated demands for a four-period planning
  horizon are 23, 86, 40, and 12. The setup cost is
  300 and the holding cost is h3 per unit per
  period.
• Enumerate all the exact requirements policies,
  compute the holding and setup costs for each, and
  find the optimal production plan.
• Solve the problem by backward dynamic programming.

9
The End