a) Find an expression for the probability of the union of three events that are mutually independent of each other. 1+5 Marks b) A computer monitor manufacturer subcontracts its major parts to four vendors: A, B, C, and D. Past records show that vendors A and C provide 30% of the requirements each, vendor B provides 25%, and vendor D provides 15%. In a random sample of 10 parts, 4 were found to be nonconforming. It is known that vendors A and C operate at a level of 5% nonconformance rate, while vendors B and D are at 10% and 15%, respectively. What is the probability that the sample came from vendor A ? From vendor B? From vendor C