Решение задачи N3052 теория вероятностей

3052. In the urn there are 4 white balls, 5 red and 3 blue. Randomly extracted one ball, without returning it back. Find the probability that the white ball appears for the first time (event A), the second time a red ball (event B), the third time a blue ball (event C).

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