A 3.558 g sample of an unknown salt containing ferrous ion was dissolved and diluted to 250.0 mL. Repeat 25.00 mL samples of the total solution were titrated with 0.01586 M KMnO4 solution, and the mean of three accepted corrected titration volumes was 13.75 mL. Calculate the %w/w of iron in the original sample mass. State your answer to 2 places after the decimal place. Do not enter units.