Q$.6(5$ points$)$

Traffic data on a State Route $($SR$)$ resulted in the following linear model:

$S=68-0\mathrm{.}68D$

where: $S=$ space mean speed $($mph$)$ and $D=$ density $($veh $\frac{?}{\text{m}\text{i}\text{l}\text{e}})$

Determine the following: a$)$ free flow speed, b$)$ jam density, c$)$ maximum flow $d)$ density at

maximum flow and e$)$ traffic flow for an average space mean speed of $50mph.$