Consider a mixture of methanol (57%), formaldehyde (23%) and a variety of other solvents. If the other solvents have an average density of 0.831 g/cm3 , estimate the density of the mixture a) assuming volume additivity and b) assuming average of the pure-component density. The density of methanol and formaldehyde are 798 kg/m3 and 815 kg/m3 , respectively