Answer
a. $C(x) = 7.24 + 0.0907x$ $(0 \leq x \leq 1000)$
b. see the graph below
c. $25.38$ dollars
d. $52.59$ dollars
e. $0.0907$
Work Step by Step
a. $C(x) = 7.24 + 0.0907x$ $(0 \leq x \leq 1000)$
b. see the graph below
c.
$C(x) = 7.24 + 0.0907x$
$C(200) = 7.24 + 0.0907(200)$
$C(200) = 25.38$
The monthly charge using $200kW$ is $25.38$ dollars
d.
$C(x) = 7.24 + 0.0907x$
$C(200) = 7.24 + 0.0907(500)$
$C(200) = 52.59$
The monthly charge using $500kW$ is $52.59$ dollars
e.
From the graph below
$\frac{y_{2}-y_{1}}{x_{2}-x_{1}} = \frac{52.59 – 25.38}{500-200}$
$m = \frac{27.21}{300}$
$m = 0.0907$
