Answer:
(b) Probabilities = 0.221404 (overall defective outcome)
 0.778596 (overall good outcome)
 
(c) EMPO = 221404.
Explanation:
concerning the question, we shall analyze it at its simplest form.
we are given error percentages and told to represent their probabilities showing their defective and good overall outcomes.
From the question, we are to provide a event tree.
(a). From the images uploaded below, we can see that the three stages 
 along with their respective probabilities of Good and Defective outcomes 
 are displayed.
 We notice here that at each stage, further branching is only possible 
 when the previous event has a good outcome, therefore, the branches 
 are discontinued after every defective outcome.
(b). The question has asked us to calculate the Overall Probability of 
 Defective and Good Overall outcomes, this can be achieved by 
 by multiplying the individual probabilities of successive events.
-  Overall Good Outcome has a probability = 0.92 * 0.93 * 0.91 = 0.778596
- Overall Defective Outcome has a probability = 1 - Probability of Overall Good outcome = 1 - 0.778596 = 0.221404
(c). So we are asked to calculate and interpret the EMPO of the process.
 Using the Overall Defective Outcome(error rate ),
 EPMO can be calculated by multiplying Overall Error Rate Probability by 1 million , that is , EPMO = 0.221404 * 1000000 = 221404.
The EPMO value simply indicates the number of defective outcomes when a million trials of the process is performed.
cheers i hope this helps.