4652. On three automatic machines, parts of the same type were manufactured in the amount of 1000, 900 and 800 pieces, respectively, and stored in one batch. Marriage in the production of machine tools is respectively 15%, 20%, 10%. Find the probability that a part taken at random from this lot is defective. Find the probability that it was made on the second machine.

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