What is the thermal efficiency of an Otto cycle where the inlet temperature T =308 K, the temperature rise(T3-T2) during the combustion process is 1,501 K and the temperature at the end of the expansion stage T4 is three times that of the inlet temperature T?(i.e. T4=3xT). You may assume isentropic processes for the expansion and compression stages. You may assume the ratio of specific heats (y) is 1.4 and the specific heat at constant volume cv=718 J/KgK. Your answer should be expressed as a percentage and be accurate to 3 significant figures (eg XX.X).