A company has total cost function $C(x)($in dollars$),$ where is $x$ is the number of items.

$C(x)=500+9x+0\mathrm{.}04x^2$

a$)$ Find the marginal cost function, $\frac{?}{\text{b}\text{a}\text{r}}(MC).$

$\frac{?}{\text{b}\text{a}\text{r}}(MC)=$

$$

b$)$ Find the marginal cost at a production level of $300$ items. $$ $ per item

$$

c$)$ Interpret your answer for part b$).$

This is the total cost to produce one item.

This is the total cost of producing $300$ items.

This is the total cost of producing $301$ items

The is the approximate cost of producing the $300$th item $.$

This is the approximate cost of producing the $301$st item.