Решение задачи N3420 теория вероятностей

3420. The student came to the exam, knowing only 20 of the 25 questions in the program. The examiner asked the student 3 questions. Using the concept of conditional probability to find the probability that a student knows all the questions. Find the same probability using the classical definition of probability.

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