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An SRS of 100 postal empl

An SRS of 100 postal employees found that the average time these employees had worked for the postal service was 7 years, with a standard deviation of 2 years. Assume the distribution of the time the population of employees has worked for the postal service is approximately normal, with mean u. Are these data evidence that u has changed fom the value of 7.5 years of 20 years ago? To determine this, we test the hypotheses Ho: u=7.5, Ha not equal to 7.5 using the one-sample test 1. Suppose the mean and standard deviation obtained were based on a sample of 25 postal workers rather than 100. The P-value would be: a) larger b) smaller c) unchanged because the difference between x-bar and the hypothesized value u=7.5 is unchanged d) unchanged because the variability measured by the standard deviation stays the same 2. A 95% confidence interval for the population mean time u that postal service employees have spent with the postal service is: a) 7 +or- 2 b) 7 +or- 1.984 c) 7 +or- 0.4 d) 7 +or- 0.2 How do you solve these?