In: Statistics and Probability
Warren W. Fisher Computer Corporation purchase 8000 transistors each year as components in minicomputers. The unit cost of each transistor is $10, and the cost of carrying one transistor in inventory for a year is $3. Ordering cost is $30 per year. Fisher operates his business 200 days per year and finds that deliveries from his supplier generally take 5 working days.
Number of transistors purchased, D = 8000
Unit cost of each transistor, C = $10
Carrying cost, H = $3
Ordering cost, S = $30
1. What is the optimal order quantity?
Optimal order quantity, Q* = sqrt ( 2DS / H )
Q* = sqrt ( 2 * 8000 * 30 / 3 ) = sqrt ( 160000 )
Q* = 400 units
Optimal order quantity = 400 units
2. What is the expected number of orders placed each year?
Expected number of orders, N = D / Q*
N = 8000 / 400 = 20 units
Expected number of orders placed = 20 units
3. What is the expected time between orders?
Expected time between orders, T = working days per year / N
Fisher operates his business 200 days per year
T = 200 / 20 = 10 days
Expected time between orders = 10 days
4. What is the total annual inventory cost?
Total annual inventory cost, TC = DC + DS / Q* + HQ* / 2
DC : Annual purchase cost
DC = 8000 * 10 = $80000
DS / Q* : Annual ordering cost
DS / Q* = 8000 * 30 / 400 = $600
HQ* / 2 : Annual Holding Cost
HQ* / 2 = 3 * 400 / 2 = $600
Total annual inventory cost, TC = 80000 + 600 + 600 = $81200
Total annual inventory cost = $81200