The answer would be 636.4 cm3 because you first have to find the volume of the sphere including the rubber wall, which is 904.32 cm3. Next, you would find the volume of the sphere inside the rubber, so subtract 2 cm from the radius of 6 cm and put 4 cm into the formula to get 267.9567. Last, subtract the internal volume from the external volume to get 636.3733 cm3 and round it to the tents place.
(4/3) x 3.14 x 6^3 = 904.32
(4/3) x 3.14 x 4^3 = 267.9467
904.32 - 267.9467 = 636.3733