Titration – Calculate thr %m/m Mn3O4.

A 0.200 g sample is analyzed for manganese as follows. Add 50.00 mL of 0.100 M ferrous ammonium sulfate to reduce MnO4 to Mn. After reduction is complete, the excess ferrous ions is titrated in acid solution with 0.0200 M KmnO4, requiring 15.0 mL. Calculate thr %m/m Mn3O4.