40. Solving a chemistry problem

80. In a volumetric flask with a capacity of 200 cm3, a solution was prepared from 2.735 g of sodium carbonate. Titration of 15 cm3 of the resulting solution in the presence of methyl orange consumes 16.65 cm3 of hydrochloric acid with a titer T = 0.00374 g/cm3. What percentage of water is contained in the sample, if it is known that it does not contain foreign impurities in appreciable quantities. What percentage more or less water is contained in the sample compared to the exact crystalline decahydrate?