Solution of problem N5319 probability theory

Solution of problem N5319 probability theory

5319. From a batch in which 10 parts without defects and 5 with defects, 3 parts are taken at random. What is the probability that:
a) all 3 parts without defects;
b) at least one item without defects.

Additional information:

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