alrighty
vsphere=(4/3)pir^3
vcylinder=hpir^2
vempty=vcylinder-2vsphere
first the cylinder volume
ok, the height=2 times the diameter=2 times 2 times radius=4 times 3.75=15 cm
the radius is 3.75
v=15pi3.75^2
v=15pi14.0625
v=210.9375pi
vsphere=(4/3)pir^2
vsphere=(4/3)pi3.75^2
vsphere=(4/3)pi14.0625
vsphere=(56.25/3)pi
vsphere=18.75pi
2vsphere=37.5pi cm^3
so vcylinder-2vsphere= 210.9375pi cm^3-37.5pi cm^3=173.4375pi cm^3
using pi=3.141592
vempty=544.8698625 cm^3
about 545 cm³