In a manufacturing plant, three machines, A, B, and C, produce 41%, 39%, and 20%, respectively, of the total production. The company's quality-control department has determined that 2.5% of the items produced by machine A, 2.5% of the items produced by machine B, and 2% of the items produced by machine C are defective. If an item is selected at random and found to be defective, what is the probability that it was produced by machine B? (Round your answer to three decimal places.)