Answer:
The minimum cost per unit is obtained for an order of 8 units.
Step-by-step explanation:
Since the total cost is modeled by;
C(x)=5x²+320
Then;
1 unit costs; C(x)=5(1)²+320 = 325
cost per unit 325/1 = 325
8 units costs; C(x)=5(8)²+320 = 640
cost per unit = 640/8 = 80
80 units costs; C(x)=5(80)²+320 = 32320
Cost per unit = 32320/80 = 404
The minimum cost per unit is obtained for an order of 8 units.