Answer:
4.525% is the percentage by volume of oxygen in the gas mixture.
Explanation:
Total pressure of the mixture = p = 4.42 atm
Partial pressure of the oxygen = 
Partial pressure of the helium = 
(Dalton law of partial pressure)





According Avogadro law:
(At temperature and pressure)
Volume occupied by oxygen gas =
Total moles of gases = n = 1 mol
Total Volume of the gases = V


Percent by volume of oxygen in the gas mixture:

Radiation
hope that helped!
Gasoline would be a mixture if I recalled