Решение задачи N5061 теория вероятностей

5061. A box contains 90 standard and 10 defective parts. The worker takes 10 pieces out of the box one after the other without returning. Find the probability that among the parts taken: a) there are no defective ones; b) at least one is defective.

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