12 times breathe give 240 ml of pure [tex]O_{2}[/tex]. Each breathe gives 20 ml of [tex]O_{2}[/tex].
Let us consider, volume of air per breathe= x ml.
Pure [tex]O_{2}[/tex] from inhaled air= [tex]\frac{20}{100}x[/tex] ml and Pure [tex]O_{2}[/tex] from exhaled air= [tex]\frac{16}{100}x[/tex] ml.
Pure [tex]O_{2}[/tex] from inhaled and exhaled air= 20 ml
So, [tex]\frac{20}{100}x[/tex] + [tex]\frac{16}{100}x[/tex] = 20
Therefore, x = 55.5 ml
So, volume of air per breath= 55.5 ml.
