The working substance of an engine is 1.00 mol of a diatomic ideal gas. The engine operates in a cycle consisting of three steps: (1) an adiabatic expansion from an initial volume of 11.0 L to a pressure of 1.00 atm and a volume of 39.6 L, (2) a compression at constant pressure to its original volume of 11.0 L, and (3) heating at constant volume to its original pressure. Find the efficiency of this cycle.