Heptane and water do not mix, and heptane has a lower density $(0\mathrm{.}684$ g$/$mL$)$ than water $(1\mathrm{.}00$ g$/$mL$).$ A $100-$mL graduated cylinder with an inside diameter of $3\mathrm{.}30$ cm contains $38\mathrm{.}2$ g of heptane and $35\mathrm{.}5$ g of water. What is the combined height of the two liquid layers in the cylinder? The volume of a cylinder is $\backslash$pi r$2$h$,$ where r is the radius and h is the height.