Решение задачи N4828 теория вероятностей

4828. There are 25 parts in a box, 19 of which are painted. Two parts are taken out at random. Find the probability that: both extracted parts will be painted; one part is painted and the other is unpainted (the order of appearance of the parts is not taken into account); at least one of the two parts will be painted.

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