8. A water tank has the geometry shown in the figure (the upper section is a cylinder with radius r and height h, and the lower section is a cone with radius r and a height of 2r). Determine the radius r if in. and the volume is 7,000 in.3. (Write an equation for the volume in terms of the radius and the height. Solve the equation for the radius, and use the double command to obtain a numerical value.)