Answer
$f(90)=900,000$
$f(95)=1,900,000$
$f(99)=9,900,000$
As $x$ approaches $100\%$, the cost gets bigger and bigger.
Work Step by Step
To find $f(90), f(95), \text{ and } f(99)$, substitute 90, 95, and 99, respectively, to $x$ to have:
$\\f(90)=\dfrac{100,000(90)}{100-90}=\dfrac{9,000,000}{10}=900,000$
Thus, cost of removing $90\%$ of the pollutants from the bayou is $\$900,000$.
$f(95)=\dfrac{100,000(95)}{100-95}=\dfrac{9,500,000}{5}=1,900,000$
Thus, cost of removing $95\%$ of the pollutants from the bayou is $\$1,900,000$.
$f(99)=\dfrac{100,000(99)}{100-99}=\dfrac{9,900,000}{5}=9,900,000$
Thus, cost of removing $99\%$ of the pollutants from the bayou is $\$9,900,000$.
