Решение задачи N4681 теория вероятностей

4681. There are products of four grades n1=2, n2=2 n3=2, n4=3. M items are taken at random to control. Determine the probability that among them m1=1 is first-class, m2=1, m3=1 and m4=2 are second, third and fourth grades, respectively.

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