Twenty pounds of a gas mixture is contained in a tank with volume 30 cubic feet at 30 psia and 70 F. The gas mixture has volumetric analysis of twenty percent carbon dioxide, thirty percent oxygen, and fifty percent nitrogen. (a) Using constant-specific heat theory, find the final temperature if 400 Btu of heat is added to the gas mixture (b) Discuss how you would solve this problem using the gas tables (discuss only, do not solve).