A construction company employs three sales engineers. Engineers 1, 2, and 3 estimate the costs of 30%, 20% and 50% of all jobs bid by the company, respectively. The chances that engineers 1, 2, and 3 make serious errors are 1%, 3%, and 2%, respectively. If a particular bid results in a serious error, what is the probability that the error was made by engineer 1? Round your answer to three decimal places.