just the last 2 questions are needed please

A mixture of methanol (methyl alcohol) and water contains 70.00% water by mass. Ideal Specific Gravity Correct. The specific gravity of water at 20C is about 0.9982; the specific gravity of methanol at 20C is about 0.7917. Assuming volume additivity of the components, estimate the specific gravity of the mixture at 20C. SG = 0.926 liters What volume of this mixture is required to provide 350.0 mol of methanol? 40.3 Actual Specific Gravity Repeat part (a) with the additional information that the specific gravity of the mixture at 20C is 0.9515 (making it unnecessary assume volume additivity). What is the real volume of the mixture required to provide 350.0 mol methanol? i liters % What percentage error results from the volume additivity assumption