Answer
$f(9)=28.4$
This tells us that 28.4 percent of college students are taking at least one online course in 2009 (which is x=9 years after 2000).
Work Step by Step
We can find $f(9)$ by plugging $x=9$ into the given equation for $f(x)$.
$f(x)=2.7x+4.1$
$f(9)=2.7\times9+4.1=24.3+4.1=28.4$