The volume of a cone is V=(1/3)(area of the base)(height)= (1/3)(pi*r^2)(h) r^2= (d/2)^2 = (d^2)/4. Given: V= 301.44cm^3 and h= 18cm. r^2= V/[(1/3)(pi)(h)] r^2= 3V/(pi)(h) (d^2)/4= 3(301.44)/(3.14)(18) d^2= 12(301.44)/(3.14)(18) d^2= 63.967 d= 7.997 d~= 8cm.