Water height =1(1+1) Cup height = 1/2* Cup height = 7.5cm

Bottom radius = 8/2 = 4cm

Water quantity = bottom area * water height =π*4*4*7.5= 120π.

Put it in the cone,

Water height =3/(3+2)* Cup height =3/5* 15=9CM.

Then the sum of the volumes of water and cone =π*4*4*9= 144π.

So the volume of the cone =144π-120π = 24π = 75.36cm2.

Don't divide by 3.