Gravimetric analysis does not always involve a precipitate. Consider the following problem. A mixture of calcium carbonate and calium oxide has a mass of 8.35 grams. When heated strongly, the CaCO3 in the sample decomposes into solid CaO and carbon dioxide gas. The calcium oxide in the original sample is not altered by heating. After heating, the mass of the sample is 6.37 grams. Using the information given, calculate the % by mass of calcium oxide in the original sample.