Q3 (a) Explain the method of retrospective study for collecting data. (2 marks) (b) Consider the semiconductor wafer dat

[answerhappygod]

Q3 A Explain The Method Of Retrospective Study For Collecting Data 2 Marks B Consider The Semiconductor Wafer Dat 1 (82.72 KiB) Viewed 35 times

Q3 (a) Explain the method of retrospective study for collecting data. (2 marks) (b) Consider the semiconductor wafer data in Table 4. Suppose those 10 wafers are selected randomly (without replacement) for an electrical test. Determine the probability that exactly 4 wafers have high contamination. (5 marks) Table 4: Wafers in Semiconductor Manufacturing Classified by Contamination and Location Location in Sputtering Tool Centre Edge 514 68 112 246 626 314 (c) A recent study on robberies for a certain city XYZ showed an average of one robbery per 20,000 people. If a city of 80,000 people, please identify the probability if three or more robberies were occurred. (6 marks) (d) Contamination Low High Total Total 582 358 The average running times of disks produced by Company A is 88.1 minutes and a standard deviation of 6.1 minutes, while Company B obtained a mean running times of 99.3 minutes with a standard deviation of 13.6 minutes. Assume the population are approximately normally distributed. Solve the probability when a random sample of 41 disks from Company B has a mean running times that at most 15 minutes more than the mean running times of a random sample of 32 disks from Company A. (7 marks)