15. Solving a chemistry problem

6. When polarography of standard solutions of lead (II) received the following. results:
С(Pb)*10-6, g/ml= 0.50;1.00;1.50; 2.00.
h, mm= 4.0; 8.0; 12.0; 16.0.
A sample of Al alloy weighing 2.500 g was dissolved and the solution was diluted to 50.00 ml. The height of the polarographic wave of lead in the obtained solution turned out to be 6.0 mm. Calculate the mass fraction (%) of lead in the analyzed sample.