Methane $($CH$4)$ is burned with dry air. The volumetric

analysis of the products on a dry basis is $5\mathrm{.}20$ percent CO$2,$

$0\mathrm{.}33$ percent CO$,11\mathrm{.}24$ percent O$2,$ and $83\mathrm{.}23$ percent N$2.$

Determine $($a$)$ the air$$fuel ratio and $($b$)$ the percentage of theoretical air used.