Решение задачи N5173 теория вероятностей

5173. There are 8 parts in a box, 5 of which are defective. The assembler draws 2 pieces at random. Find the probability that
a) the extracted parts are of high quality;
b) among the extracted 1 defective part and 1 quality part.

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