A volume of 0.3 m3 of O2 at 200 K and 8 MPa is mixed with 0.5 m3 N2 at the same temperature and pressure, forming a mixture at 200 K and 8 MPa. Determine the volume of the mixture, using (a) the ideal-gas equation of state, (b) Kay's rule, and (c) the compressibility chart and Amagat's law.