Question 1154329
*[illustration frustum1.png].
Volume of Frustum of a cone = {{{(pi*h/3)(R^2+r^2+rR)}}}

here R =11, r=5, h=18 

plug values
(6*pi)*(11^2+5^2+55) =3789 cm^3

1 liter = 1000 cm^3

3,789 liters is required