Решение задачи N3715 теория вероятностей Байеса

3715. Two operators filled in the same set of punched cards. The probability that the first operator makes a mistake is 0.1; for the second operator, this probability is 0.2. An error was found when checking the punched cards. What is the probability that the first statement was wrong?

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