3. A portion of 1.063 g of the analyte containing calcium was dissolved, 25.00 ml of H2C2O4 solution was added, and a CaC2O4 precipitate was obtained. The solutions after filtering and washing the precipitate were collected in a volumetric flask with a capacity of 200.0 ml and made up to the mark with water. When titrating 50.00 ml of the resulting solution, 4.85 ml of 0.1090 N was consumed. KMnO4 solution (f equiv. = 1/5). To determine the concentration of the working solution of oxalic acid, 50.00 ml, it was diluted to 200.0 ml, 50.00 ml was taken, and 48.2 ml of KMnO4 solution was titrated. Calculate the mass fraction of calcium oxide in the analyzed substance.

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