Consider a simple cold air-standard Brayton cycle where air enters the compressor at 1 bar and 27 C. The pressure ratios in the compressor and the turbine are 5. The temperature of the air entering the turbine is 1150 C. Calculate the thermal efficiency of the cycle (a) if processes in turbine and compressor are ideal and (b) if the isentropic efficiencies of the turbine and compressor are 0.75 and 0.65, respectively.