A mixture containing aluminum tetrafluoroborate, Al(BF4) (FW 287.39) and magnesium nitrate Mg(NO3)2 (FW 148.31) weighed 0.2828 g. It was dissolved in 1 wt % aqueous HF and treated with nitron solution to precipitate a mixture of nitron tetrfluoroborate and nitron nitrate weighing 1.322 g. Find the weight percent of Mg in the original mixture.