Решение задачи N4663 теория вероятностей

4663. There are products of four grades, and the number of products of each grade is, respectively, 4, 2, 2, 2. For control, 7 products are taken at random. Determine the probability that among them 3 is a first-class item, 1 is a second-grade item, 2 is a third-grade item, and 1 is a fourth-grade item.

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