Answer
a) \$403
b) \$7
c) The average cost decreases when more DVDs are produced. This is illustrated by parts (a) and (b) - the cost is much less when we produce 100 DVDs than when we produce 1 DVD.
Work Step by Step
a) $x$ represents the number of DVDs. To calculate the average cost for 1 DVD, we plug in 1 for $x$:
$\frac{3x + 400}{x} = \frac{3\cdot 1 + 400}{1} = 3 + 400 = 403$
b) Once again, $x$ represents the number of DVDs. In this part we plug in 100 for $x$:
$\frac{3x+400}{x} = \frac{3\cdot 100 + 400}{100} = \frac{700}{100} = 7$
c) if you graph the equation, you'll see that the graph slopes downwards when $x \gt 0$. This indicates that the average cost is decreasing.
