The efficiency of a machine is the ratio between the output power and the power in input: [tex]\epsilon = \frac{P_{out}}{P_{in}} [/tex] in our problem, the output power is 3760 W while the input power is 4000 W, so the efficiency is [tex]\epsilon = \frac{3760 W}{4000 W} =0.94 [/tex] So the efficiency of the machine is 94%.
