A new production process at Fabulast, Inc., has two in-line stages. The probability of defective components being produced in stage 1 is 15 percent and 10 percent in stage 2. Assembled units that have defective components only from stage 1 OR only from stage 2 are considered repairable. However, items that have defective components from both stage 1 and stage 2 (completely defective) must be scrapped.
a) Use a probability tree diagram and calculate the probabilities that the Fabulast assembled units are:
defective in stage 1 and defective in stage 2 (are completely defective);
defective in stage 1 and are not defective in stage 2 (called Repairable I);
not defective in stage 1 but are defective in stage 2 (called Repairable II); and
not defective in stage 1 and are not defective in stage 2 (completely good).
What is the probability of producing repairable assembled units?
b) Explain the results in terms of the multiplication and the addition rules for probability.