Solution of problem N3830 probability theory total prob

Solution of problem N3830 probability theory total prob

3830. Casting in blanks come from three preparation shops: 60 pcs. from the first workshop, and from the second and third workshops, respectively, two and four times more than from the first. At the same time, the material of the first workshop has 10% of defects, the second - 20% of defects, and the third - 25%. Find the probability that a blank disc is found to be defect free.

Additional information:

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