114. Solving a chemistry problem

503. A sample weighing 0.455 g containing potassium nitrite with an admixture of potassium sulfate was dissolved in water and 250 ml of solution was obtained. For titration of 10 ml of a standard 0.01 mol/l solution of potassium permanganate with F0.01=1.015 in a sulfuric acid medium, 13.05 ml of the prepared solution of potassium nitrite was used. Determine the mass composition of the analyzed mixture in%.