In: Operations Management
Ergonomics Inc. sells ergonomically designed office chairs. The company has the following information:
Average demand = 35 units per day
Average lead time = 49 days
Item unit cost = $69 for orders of less than 390 units
Item unit cost = $65 for orders of 390 units or more
Ordering cost = $44
Inventory carrying cost = 20%
The business year is 250 days
Assume there is no uncertainty at all about the demand or the lead time.
a. Calculate EOQ if unit cost is $69 and $65. (Note: These EOQs do not need to be feasible in their price range.) (Round up your answers to the next whole number.)
b. Calculate annual ordering costs for each alternative? (Round your answers to 2 decimal places.)
c. Calculate annual inventory carrying costs for each alternative? (Round your answers to 2 decimal places.)
d. Calculate annual product costs for each alternative?
e. What will be the total costs for each alternative? (Round your answers to 2 decimal places.)
f. Based on your analysis, how many chairs should they order at a time? (Round your answers to 2 decimal places.)
g. How much the firm can save annually by using the order quantity in Part f. instead of the first EOQ shown in Part a? (Round your answer to 2 decimal places.)
Average demand d = 35 units per day
Annual demand D = 35*250 days = 8750
Average lead time L = 49 days
Item unit cost C = $69 for orders of less than 390 units
= $65 for orders of 390 units or more
Ordering cost S = $44
Inventory carrying cost = 20%
H = 0.2*69 = 13.8 for orders of less than 390 units
H = 0.2*65 = 13 for orders of 390 units or more
The business year is 250 days
a)
Unit cost is $69
EOQ = 236 units (Feasible)
Unit cost is $65
EOQ = 243 units (Not Feasible)
b)
We calculate the costs at Q = 236 and 390
Q = 236
Annual ordering costs = (D/Q)S = (8750/236)*44 = 1631.36
Q = 390
Annual ordering costs = (D/Q)S = (8750/390)*44 = 987.18
c)
Q = 236
Annual inventory carrying costs = (Q/2)H = (236/2)*13.8 = 1628.4
Q = 390
Annual inventory carrying costs = (Q/2)H = (390/2)*13 = 2535
d)
Q = 236
Annual production costs = DC = 8750*69 = 603750
Q = 390
Annual production costs = DC = 8750*65 = 568750
e)
Total cost = Annual production costs + Annual ordering costs + Annual inventory carrying costs
Q = 236
Total cost = 603750 + 1628.4 + 1631.36 = 607009.76
Q = 390
Total cost = 568750 + 2535+987.18 = 572272.18
f)
They should order 390 chairs as the total cost is less when compare with EOQ = 236
g) Savings= 607009.76 - 572272.18 = 34738.58