As a gasoline engine is running, an amount of gasoline containing 14,000 J of chemical potential energy is burned in 1 s. During that second, the engine does 3,500 J of work.

What is the engine's efficiency (in percent)?

The burning gasoline has a temperature of about 4,200F (2,600 K). The waste heat from the engine flows into air at about 88F (304 K). What is the Carnot efficiency (in percent) of a heat engine operating between these two temperatures?