A hollow brass cylinder is weighed on a pan balance (kitchen scale) which read in kg. The scale reading is 5.56 kg. The brass cylinder is now removed from the scale and is replaced by a beaker of liquid density 1.56 * 10^3 kg/m^3; the scale now reads 17.50 kg. The brass cylinder is then suspended from a thread, and it is lowered into the liquid until it is completely immersed but does not touch the bottom of the beaker. The reading of the balance increases from 17.50 kg to 28.28 kg when the cylinder is immersed in the liquid. The density of brass is 8.47 * 10^3 kg/m^3.
(I) Calculate the volume of metal in the cylinder.
(II) Calculate the upthrust (buoyancy force) exerted on the hollow cylinder when it is totally immersed in the liquid.
(III) Calculate the volume of the hollow space inside the cylinder.
Please help on II and III