A factory has two production lines A and B, production line A works 7 days a week, production line B works only 5 days a week. Production line A produces 5000 items each day where 80% of the produced items are high quality and the rest are of medium quality. Production line B produces 3500 items each day where 70% of the produced items are high quality, 19% medium quality, and the rest are of low quality. All items produced after working for many weeks are accumulated in a warehouse. If an item is tested and found to be of medium quality, what is the probability that it was produced by production line A. l [The answer should be a number rounded to ve decimal places, don't use symbols such as %]