A modified atmosphere requires higher$-$than$-$normal amounts of oxygen but sparing amounts of water vapor. You have two streams available for mixing: stream A is dry air $(79\%$ N$2,21\%$ O$2),$ and stream B is enriched air saturated with water vapor $(4\mathrm{.}64\%$ water vapor, $62\mathrm{.}76\%$ O$2,$ and balance N$2).$ The desired product should contain $0\mathrm{.}56\%$ water vapor. Determine the oxygen content $($mole fraction$)$ of the product stream.