A certain natural gas has the following volumetric analysis: 65 percent CH4, 8 percent H2, 18 percent

Question:

A certain natural gas has the following volumetric analysis: 65 percent CH4, 8 percent H2, 18 percent N2, 3 percent O2, and 6 percent CO2. This gas is now burned completely with the stoichiometric amount of dry air. What is the air–fuel ratio for this combustion process?