3920. All products of the shop are checked by two controllers, the first controller checking 55% of products, and the second one checking the rest. The probability that the first controller will miss a non-standard product is 0.01, the second is 0.02. Taken at random, the product labeled as standard turned out to be non-standard. Find the probability that this product was tested by a second controller.

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