$15-8$

Given a sag vertical curve connecting a $1\mathrm{.}5\%$ grade with a $+2\mathrm{.}5\%$ grade on a rural arterial highway, use the rate of vertical curvature and a design speed of $70$ mi$/$h to compute the elevation of the curve at $100$ ft stations if the grades intersect at station $(475+00)$ at an elevation of $300\mathrm{.}00$ ft $.$ Identify the station and elevation of the low point.