Question

Questions11and12 are based on the following information: An investigation of the effectiveness of a training program to improve customer relationships included a pre-training and post-training customer survey, 12 customers were randomly selected to score the customer relationships both before and after the training. The differences of scores are calculated as the post-training survey score minus the pre-training survey score. The sample mean difference of scores is 0.5. The test statistic is 1.03 for testing whether the population mean difference µD ≤0.

11. Based on the above information,the sample standard deviation of the differences of scores is .

A. 1.49

B. 1.53

C. 1.48

D. 1.68
12. Suppose that we want to test whether the training program improved the customer relationships,the null hypothesis is µD ≤0. Which of the following is correct?

A. At the 0.05 significance level,we reject the null,the training program improved customer relationships.

B. At the 0.05 significance level, we do not reject the null, the training program did not improve customer relationships.

C. At the 0.10 significance level, we do not reject the null, the training program did not improve customer relationships.

D. At the 0.10 significance level, we reject the null because the test statistic is greater than the critical value 1.645.

.

Answer 1