One type of breathalyzer employs a fuel cell to measure the quantity of alcohol in the breath. When a suspect blows into the breathalyzer, ethyl alcohol is oxidized to acetic acid at the anode:

CH3CH2OH(g)+4OH−(aq)→HC2H3O2(g)+3H2 O(l)+4e−

At the cathode, oxygen is reduced:
O2(g)+2H2O(l)+4e−→4OH−(aq)

The overall reaction is the oxidation of ethyl alcohol to acetic acid and water. When a suspected drunk driver blows 186 mL of his breath through this breathalyzer, the breathalyzer produces an average of 320 mA of current for 10 s.

Required:
Assuming a pressure of 1.0 atm and a temperature of 26C, what percent (by volume) of the driver's breath is ethanol?