In: Operations Management
Maxima distributor uses 500 units of an office supply per year. The cost of the office supply is $60/unit, for orders of less than 50 units; $55/unit for orders greater or equal to 50. The inventory holding cost is 20% of its unit price per year. The procurement order setup cost is $15/order. What is the optimum purchase order quantity that Maxima should place and what is the total cost? (TCO=KD/Q+hQ/2+cD)
Scenario 1: The cost of the office supply is $60/unit, for orders of less than 50 units
Unit cost = $60 / unit
A = Annual Requirement = 500 units
O = Ordering cost / order = $ 15 / order
C = Carrying cost / unit / annum= $ 60 x 20% = $ 12
EOQ = √2AO/C
= √2*500*15/12
=√15000/12
=√1250
=35.36 units
Thus EOQ ≈ 35 units
No. of order = 500 / EOQ = 500/35 =14.29 orders ≈ 14 orders
Ordering cost = No. of orders x Ordering cost per order = 14 x $ 15 = $ 210
Carrying cost = (EOQ/2) x Carrying cost per unit per annum = (35/2) x 12 = $ 210
Total Cost = Ordering cost + Carrying cost = 210+210 = $ 420
Cost of units of Office supply in the year = 500 units x $ 60 = $ 30000
Total cost inclusive of unit cost = 30000+210+210 = $ 30420
Scenario 2: The cost of the office supply is $55/unit, for orders of greater than or equal to 50 units
Unit cost = $55 / unit
A = Annual Requirement = 500 units
O = Ordering cost / order = $ 15 / order
C = Carrying cost / unit / annum= $ 55 x 20% = $ 11
EOQ = √2AO/C
= √2*500*15/11
=√15000/11
=36.93 units
Thus EOQ ≈ 37 units
Since in this also EOQ is coming less than 50 so this scenario is invalid (as it was assumed that the order quantity is greater than or equal to 50 units)
Hence, final answer can be drawn from scenario 1:
Optimum purchase order quantity = EOQ of scenario 1 = 35 units per order
Total cost:
Total Cost = Ordering cost + Carrying cost = 210+210 = $ 420
Cost of units of Office supply in the year = 500 units x $ 60 = $ 30000
Total cost inclusive of unit cost = 30000+210+210 = $ 30420
Total cost (inclusive of unit cost) = 30000+210+210 = $ 30420