The percentage of the mass of cellulose can be calculated by dividing the mass of the mass of cellulose in the sample by the total mass of the sample and then multiplying the output by 100 to get the percentage.
Mass of cellulose in sample = 0.38 grams
Total mass of sample = 3.35 + 0.38 + 8.76 = 12.49 grams
mass percent of cellulose = (0.38/12.49) x 100 = 3.0424%
