In a study designed to test the effectiveness of acupuncture for treating migraine, 142 subjects

were treated with acupuncture. The numbers of migraine attacks for the treatment group had a

mean of 1.8 and a standard deviation of 1.4. Construct a 95% confidence interval estimate of the mean number of migraine attacks for all people treated with acupuncture.

1.6
1.7
1.5
1.3

If your score on your next statistics test is converted to a z score, which of these z scores would you prefer: minus2.00, minus1.00, 0, 1.00, 2.00? why? a. the z score of 2.00 is most preferable because it is 2.00 standard deviations above the mean and would correspond to the highest of the five different possible test scores. b. the z score of 0 is most preferable because it corresponds to a test score equal to the mean. c. the z score of minus2.00 is most preferable because it is 2.00 standard deviations below the mean and would correspond to the highest of the five different possible test scores. d. the z score of minus1.00 is most preferable because it is 1.00 standard deviation below the mean and would correspond to an above average