124. Solving a chemistry problem

2. A 0.2325 g sample of the mineral containing Al was dissolved and, after appropriate treatment, the solution was diluted in a volumetric flask with water to 100 ml. When polarography of 10 ml of this solution, the wave height was equal to 6.15 mm. After adding 0.5 ml of the Al3 standard solution (T=0.000027 g/ml), the wave height increased to 7.00 mm. Determine the percentage of Al2O3 in the mineral.