The height of a hiker in feet is modeled by the function $h(d)=0.5 d^2+810$, where $d$ is the number of $\text{km}$ hiked. The rate of change of $d$ with respect to time is given by $\frac{dd}{dt}=\sqrt[3]{10 d+4}\text{ km/hr}$. Find $\frac{dh}{dt}$, in feet/hr, when the hiker has hiked $6\text{ km}$ ($d=6$).