076. Solving a chemistry problem

45. To determine zirconium in the alloy, a sample weighing 0.2000 g was dissolved and the resulting solution was diluted to 100.0 ml. 2.00 ml of the test solution was taken into a 50.0 ml volumetric flask, a zirconin solution was added, and the volume of the solution in the flask was adjusted to the mark with water. The optical density of this solution at λ=610 nm relative to the reference solution containing 1.00 mg of zirconium in 50.0 ml is 0.380. Optical densities of standard solutions containing 1.25 in 50.0 ml; 1.50; 1.75 and 2.00 mg of zirconium turned out to be equal to 0.300, respectively; 0.350; 0.410; 0.465. Calculate the zirconium content in the alloy.