Answer
$\approx 540$ ft.
Work Step by Step
$v(t)=\displaystyle \frac{d}{dt}[s(t)]$
so
the distance traveled is $\displaystyle \int_{0}^{8}v(t)dt$.
We estimate the area under the curve from $0\leq t\leq 8$ to be
around 18 squares,
each square representing (2s)$\times$(15 ft/s)=30 ft
18(30) $\approx 540$ ft.