Solution of problem N3792 probability theory total prob

3792. The box contains 4 parts belonging to workshop No. 1, 3 details — workshop No. 2, and 5 details — workshop No. 3. The probability that a part will be defective for workshop No. 1 is 0.02, for workshop No. 2 - 0 , 12, and shop number 3 produces 5% of the marriage. At random, the Quality Control Department selects the part to be checked, find the probability that it will be standard.