A three-stage reciprocating compressor compresses air from 1 bar and 26 °C to 36 bar with pv^{1.3} = constant in all stages. Assuming perfect intercooling and no clearance, find (a) the minimum power required to compress 0.25 m³/s of free air (at the intake state) and (b) the two intermediate pressures (answers in kW and bar).