3907. The company manufactures locks. The first workshop produces 25, the second-35, the third-40% of all locks. Marriage is 5%, 4% and 2% respectively.
a) find the probability that the selected lock is defective.
b) A randomly selected lock is defective. What is the probability that it is made in 1 workshop.

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