1. Engr Thomas Pendot wants to construct a frustum from a right circular cone. At what distance from the base of the right circular cone must a plane be passed parallel to the base in order that the volume of his frustum formed shall be three-fifths of the volume of the given cone?
2. A cylindrical glass 5 inches in diameter and 8 inches in altitude is filled with iced tea. It is then titled to a position enough for the iced tea level to coincide with the center of the base. How much iced tea is drained from the glass?
1. The part cut off of the frustum will be 2/5 of the original cone, so the smaller cone is$\frac{2h\pi r^2}{15}$ of the original cone, so the smaller cone's height is $^3\sqrt{\frac25}$, so the height is $\boxed{\frac{^3\sqrt5-^3\sqrt2}{^3\sqrt5}}$ of the original cone.