3781. The warehouse received the products of three factories. The production volumes of the first, second and third factories are respectively 2: 5: 3. It is also known that the average percentage of non-standard products among the products of the first factory is - 3, the second - 2, the third - 1%. Find the probability that a product taken at random is produced at the first factory, if it turned out to be non-standard.

Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)