Question 867306
The radius at any level and the distance from center to tip are in proportion. Make a drawing.  See then that {{{4/12=r/9}}}; this means radius at the current fulled level for this inverted cone is {{{r=(4/12)9=(1/3)9=3}}}.


Volume formula for a cone is {{{(1/3)h*pi*r^2}}};
You know these now:
h=9, and r=3;
.
.
...The FORMULA!