Решение задачи N2985 теория вероятностей

2985. In the group of students consisting of 20 people, 12 boys and 8 girls. Two students were randomly selected for duty. What is the probability that among them will be:
a) one young man and one girl;
b) both young men;
c) both girls?

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