Решение задачи N3044 теория вероятностей

3044. In the box 20 balls, of which 5 are green and 15 are red. 2 balls are successively taken out of the box; The first ball in the box does not return. Find the probability that the first ball is turned out to be green, and the second - red.

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