From the periodic table:
molar mass of barium = 137.2 grams
molar mass of oxygen = 16 grams
molar mass of hydrogen = 1 gram
molar mass of Ba(OH)2 = 137.2 + 2(16) + 2(1) = 171.2 grams
molar mass of 4H2O = 4 [2(1) + 16] = 72 grams
molar mass of Ba(OH)2.4H2O = 171.2 + 72 = 243.2 grams
Therefore, each 243.2 grams of barium hydroxide tetrahydrate contains 72 grams of water, thus, 92.8 grams will contain:
mass of water in 92.8 grams = (92.8 x 72) / 243.2 = 27.474 grams
Based on this, when a 92.8 gram sample of Ba(OH)2•4H2O (barium hydroxide tetrahydrate) is heated until water is released, 27.474 grams of water will be released.