Решение задачи N4685 теория вероятностей

4685. There are products of four grades, and the number of products of each grade is, respectively, 3, 1, 2, 3. For control, 4 products are taken at random. Determine the probability that among them 0 is a first-class item, 1 is a second-grade item, 1 is a third-grade item, and 2 is a fourth-grade item.

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