4. Titanium in steel was determined by the photometric addition method under the following conditions: sample weight = 0.150 g, solution volume 100 ml. Cuvette l = 1 cm. 20 ml reagent was added to 25 ml of the resulting solution and diluted with water to the mark up to 50 ml. To the second portion of 25 ml was added 5 ml of a standard solution of titanium with a concentration of 0.04 mg/ml, 20 ml of the reagent. The total volume of the solution was 50 ml. The optical density of the first solution turned out to be 0.33. and the second 0.64. What is the percentage of titanium in the steel sample?