The coefficient of performance

An air conditioner operating at steady state maintains a dwelling at 20°C on a day when the outside temperature is 35°C. Energy is removed by heat transfer from the dwelling at a rate of 4 kW while the air conditioner's power input is 1 kW. Determine (a) the coefficient of performance of the air conditioner and whether the cycle operates reversibly, operates irreversibly, or is impossible and (b) the power input required by a reversible refrigeration cycle providing the same cooling effect while operating between hot and cold reservoirs at 35 °C and 20 °C, respectively. (Watch "Carnot Refrigeration Examples")