A rigid, well-insulated tank with a volume of 3 fe contains air at P1= 22 lbf/in2 and T1= 475 •R. The air is stirred by a paddle wheel, resulting in an energy transfer to the gas of magnitude 4680 ft-lbf. Assuming ideal gas behavior for the air and neglecting kinetic and potential energy effects, determine the: a) Mass of the air b) Final temperature in oR c) Final pressure in psi.