4. Superheated steam at 20 MPa, 560 C enters the turbine of a vapor power plant. The pressure at the exit of the turbine is 0.5 bar, and liquid leaves the condenser at 0.4 bar at 75 C. The pressure in increase to 20.1 MPa across the pump. The turbine and pump have isentropic efficiencies of 81% and 85% respectively. Cooling water enters the condenser at 20 C with a mass flow rate of 70.7 kg/s and exits the condenser at 38 C. For the cycle, determine (a) the mass flow rate of steam, in kg/s, and (b) the thermal efficiency of the power plant.