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Ergonomics Inc. sells ergonomically designed office chairs. The company has the

ID: 361140 • Letter: E

Question

Ergonomics Inc. sells ergonomically designed office chairs. The company has the following information:

Average demand = 22 units per day

Average lead time = 38 days

Item unit cost = $58 for orders of less than 280 units

Item unit cost = $56 for orders of 280 units or more

Ordering cost = $33

Inventory carrying cost = 25%

The business year is 250 days

Assume there is no uncertainty at all about the demand or the lead time.

1) Calculate EOQ if unit cost is $58 and $56. (Note: These EOQs do not need to be feasible in their price range.)

Item unit cost = $58

Item unit cost = $56

2) Calculate annual ordering costs for each alternative?

Item unit cost = $58

Item unit cost = $56

3) Calculate annual inventory carrying costs for each alternative?

Item unit cost = $58

Item unit cost = $56

4) Calculate annual product costs for each alternative?

Item unit cost = $58

Item unit cost = $56

5) What will be the total costs for each alternative?

Item unit cost = $58

Item unit cost = $56

6) Based on your analysis, how many chairs should they order at a time?

7) How much the firm can save annually by using the order quantity in Part f. instead of the first EOQ shown in Part a?

Explanation / Answer

Let, D = annual demand = 22 x 250 = 5500

U = unit cost = 58 (if order < 280 units), 56 (if order >= 280)

C = Order cost = $33

H = inventory carrying cost = 25%

EOQ at $58: Sqrt (2 x 5500 x 33/ 58 x .25) = 158 units

EOQ at $56: Sqrt (2 x 5500 x 33/ 56 x .25) = 161 units

TAC of ordering at 158 units:

Annual ordering cost = 33(5500/158) = $1148.4

Annual inventory carrying cost = 58 x .25 (158/2) = $1145.5

Annual Product cost = 58 x 5500 = $319,000

Total Cost = $321,294

TAC of ordering 161 units:

Annual ordering cost = 33(5500/ 161) = 1127.3

Annual inventory carrying cost = 56 x .25 (161/2) = $1127

Annual Product cost = 56 x 5500 = $308,000

Total cost = $310,254

Therefore, 161 chairs should be ordered at a time.