Решение задачи N2748 теория вероятностей

2748. In a group of 10 students there are 3 excellent students. Four students were selected at random on the list. Find the probability that among them:
1) three excellent students;
2) at least one excellent student;
3) excellent students and non-excellent students equally.

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