Can someone please help me with this problem Thanks.

What volume of air contains 11.8 of oxygen gas at 273 and 1.00 . the mole fraction of oxygen gas in air is 0.21.

I use PV=nRT where V= nRT/P and n = 11.8 g x.21 / 32 = 0.077 then I plug that and the rest into the equation but did not get the correct answer.