Average Costs $\bar { C } ( x ) = 5 x + \frac { 4500 } { x } , \quad x > 0$

Multiple Choice

Average costs. Suppose the average costs of a mining operation depend on the number of machines used, and average costs, in dollars, are given by $\bar { C } ( x ) = 5 x + \frac { 4500 } { x } , \quad x > 0$ , where x is the number of machines used. What is the minimum average cost?

A) $0
B) $30
C) $300
D) $150
E) $4505