# an experiment was designed to estimate the mean difference in weight

upper limit: __________

5) If a random sample of 24 homes south of Center Street in Provo has a mean selling price of \$145,375 and a standard deviation of \$4750, and a random sample of 24 homes north of Center Street has a mean selling price of \$148,600 and a standard deviation of \$5900, can you conclude that there is a significant difference between the selling price of homes in these two areas of Provo at the 0.05 level? Assume normality.

(ii) Find the p-value. (Give your answer correct to four decimal places.)

(b) State the appropriate conclusion. (choose one)

Re   a) Reject the null hypothesis, there is not significant evidence of a difference in means.

b) Reject the null hypothesis, there is significant evidence of a difference in means.

c) Fail to reject the null hypothesis, there is significant evidence of a difference in means.

d) Fail to reject the null hypothesis, there is not significant evidence of a difference in means.

6) A study titled “Factors Leading to Reduced Intraocular Pressure after Combined Trabeculotomy and Cataract Surgery” in the Journal of Glaucoma investigated the influence cataract surgery alone and cataract surgery with trabeculotomy has on eye pressure. Two groups were formed for each type of surgery and were compared for similarities with respect to several factors beforehand. No significant difference was found between the two groups with respect to the number of preoperative glaucoma medications the patient was taking. Suppose a similar study involving six patients receiving the combined surgery and five patients receiving the cataract surgery alone produced the following values of number of medications. Using the Mann-Whitney U test, determine whether the two groups are the same with respect to number of medications. Use α = .05.

 Combined Surgery 3 1 4 0 1 2 Cataract Surgery Only 3 1 0 1 2

(a)  Find U

(ii) Find the critical U-value.
U critical    ____________

(b) State the appropriate conclusion. (choose one)

Re a) Reject the null hypothesis, there is significant evidence that the number of medications differ.

b) Reject the null hypothesis, there is not significant evidence that the number of medications differ.

c) Fail to reject t1) An experiment was designed to estimate the mean difference in weight gain for pigs fed ration A as compared with those fed ration B. Eight pairs of pigs were used. The pigs within each pair were litter-mates. The rations were assigned at random to the two animals within each pair. The gains (in pounds) after 45 days are shown in the following table. Assuming weight gain is normal, find the 95% confidence interval estimate for the mean of the differences μd, where d = ration A – ration B. (Give your answers correct to two decimal places.)

Litter

1

2

3

4

5

6

7

8

Ration A

39

58

58

46

52

60

47

49

Ration B

35

48

52

38

42

58

39

42

Lower Limit: _________

Upper Limit: _________

2) Consider the following hypothesis test for the mean difference. (Give your answers correct to four decimal places.)

(a) Determine the p-value for Hoμd = 0 and Haμd > 0, with n = 16 and t = 1.99.

(b) Determine the p-value for Hoμd = 0 and Haμd  0, with n = 24 and t = -1.93.

(c) Determine the p-value for Hoμd = 0 and Haμd < 0, with n = 34 and t = -2.67.

(d) Determine the p-value for Hoμd = 0.75 and Haμd > 0.75, with n = 15 and t = 3.47.

3) Ten randomly selected college students, who participated in a learning community, were given pre–self-esteem and post–self-esteem surveys. A learning community is a group of students who take two or more courses together. Typically, each learning community has a theme, and the faculty involved coordinate assignments linking the courses. Research has shown that the benefits of higher self-esteem, higher grade point averages (GPAs), and improved satisfaction in courses, as well as better retention rates, result from involvement in a learning community. The scores on the surveys are as follows.

 Student 1 2 3 4 5 6 7 8 9 10 Prescore 23 21 11 22 17 13 17 12 15 14 Postscore 13 19 17 22 12 17 12 13 13 25

Does this sample of students show sufficient evidence that self-esteem scores were higher after participation in a learning community? Lower scores indicate higher self-esteem. Use the 0.05 level of significance and assume normality of scores.

(ii) Find the p-value. (Give your answer correct to three decimal places.)

(b) State the appropriate conclusion. (choose one)

Faa) Fail to reject H0. At the 0.05 level of significance, there is sufficient evidence to show that one’s self esteem increases after participation in a learning community.

b)  b) Reject H0. At the 0.05 level of significance, there is insufficient evidence to show that one’s self esteem increases after participation in a learning community.

c) Reject H0. At the 0.05 level of significance, there is sufficient evidence to show that one’s self esteem increases after participation in a learning community.

d) Fail to reject H0. At the 0.05 level of significance, there is insufficient evidence to show that one’s self esteem increases after participation in a learning community.

4) A study comparing attitudes toward death was conducted in which organ donors (individuals who had signed organ donor cards) were compared with nondonors. Templer’s Death Anxiety Scale (DAS) was administered to both groups. On this scale, high scores indicate high anxiety concerning death. The results were reported as follows.

 n Mean Std. Dev. Organ Donors 28 5.09 2.75 Nonorgan Donors 74 7.24 3.38

Construct the 95% confidence interval for the difference between the means, μnon − μdonor. (Estimate df by using the smaller value of dfdonor and dfnon.)

lower limit: __________

upper limit: __________

5) If a random sample of 24 homes south of Center Street in Provo has a mean selling price of \$145,375 and a standard deviation of \$4750, and a random sample of 24 homes north of Center Street has a mean selling price of \$148,600 and a standard deviation of \$5900, can you conclude that there is a significant difference between the selling price of homes in these two areas of Provo at the 0.05 level? Assume normality.

(ii) Find the p-value. (Give your answer correct to four decimal places.)

(b) State the appropriate conclusion. (choose one)

Re   a) Reject the null hypothesis, there is not significant evidence of a difference in means.

b) Reject the null hypothesis, there is significant evidence of a difference in means.

c) Fail to reject the null hypothesis, there is significant evidence of a difference in means.

d) Fail to reject the null hypothesis, there is not significant evidence of a difference in means.

6) A study titled “Factors Leading to Reduced Intraocular Pressure after Combined Trabeculotomy and Cataract Surgery” in the Journal of Glaucoma investigated the influence cataract surgery alone and cataract surgery with trabeculotomy has on eye pressure. Two groups were formed for each type of surgery and were compared for similarities with respect to several factors beforehand. No significant difference was found between the two groups with respect to the number of preoperative glaucoma medications the patient was taking. Suppose a similar study involving six patients receiving the combined surgery and five patients receiving the cataract surgery alone produced the following values of number of medications. Using the Mann-Whitney U test, determine whether the two groups are the same with respect to number of medications. Use α = .05.

 Combined Surgery 3 1 4 0 1 2 Cataract Surgery Only 3 1 0 1 2

(a)  Find U

(ii) Find the critical U-value.
U critical    ____________

(b) State the appropriate conclusion. (choose one)

Re a) Reject the null hypothesis, there is significant evidence that the number of medications differ.

b) Reject the null hypothesis, there is not significant evidence that the number of medications differ.

c) Fail to reject the null hypothesis, there is significant evidence that the number of medications differ.

d) Fail to reject the null hypothesis, there is not significant evidence that the number of medications differ.

he null hypothesis, there is significant evidence that the number of medications differ.

d) Fail to reject the null hypothesis, there is not significant evidence that the number of medications differ.