The volume of the tank is 51*39*28 = 55692 cm^3. The volume of the empty part of the tank is 5% of it, i.e. 0.05*55692 = 2784.6 cm^3. The volume of the cylinder is= = 3454 cm^3. Since the cylinder is fully submerged into water, the volume of water which is spilled out is 3455 - 2784.6 = 669.4 cm^3.