McAlister Company is operating at capacity and desires to add a new service to its rapidly expanding business. The service should be added as long as service revenues exceed: the sum of variable costs, fixed costs, and any related opportunity costs. the sum of variable costs and fixed costs. variable costs. the sum of variable costs and any related opportunity costs. fixed costs.

Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.