probability/stat

9- A quality inspector selects a sample of 12 items at random from a collection of 60 items, of which 18 have excellent quality, 25 have good quality, 12 have poor quality, and 5 are defective. (a) What is the probability that the sample only contains items that have either excellent or good quality? (b) What is the probability that the sample contains three items of excellent quality, three items of good quality, three items of poor quality, and three defective items? 10- A random sample of 10 fibers is taken from a collection of 92 fibers that consists of 43 fibers of polymer A, 17 fibers of polymer B, and 32 fibers of polymer C. (a) What is the probability that the sample does not contain any fibers of polymer B? (b) What is the probability that the sample contains exactly one fiber of polymer B? (c) What is the probability that the sample contains three fibers of polymer A, three fibers of polymer B, and four fibers of polymer C? 11- An oil company is bidding for the rights to drill a well in field A and a well in field B. The probability it will drill a well in field A is 40%. If it does, the probability the well will be successful is 45%. The probability it will drill a well in field B is 30%. If it does, the probability the well will be successful is 55% Calculate each of the following probabilities using tree diagram: (a) probability of a successful well in field A (b) probability of a successful well in field B 12- A car repair can be performed either on time or late and either satisfactorily or unsatisfactorily. The probability of a repair being on time and satisfactory is 0.26. The probability of a repair being on time is 0.74. The probability of a repair being satisfactory is 0.41. What is the probability of a repair being late and unsatisfactory