in a random sample of 100 parts ordered from vendor a, 12 were defective. in a random sample of 200 parts ordered from vendor b, 10 were defective. a. estimate the proportion of parts from vendor a that are defective, and find the uncertainty in the estimate. b. estimate the proportion of parts from vendor b that are defective, and find the uncertainty in the estimate. c. estimate the difference in the proportions, and find the uncertainty in the estimate