What is the estimated 95% confidence interval (CI) of the average difference in blood vitamin D levels between US landscapers and office workers in ng/mL? Assign groups 1 and 2 to be landscapers and office workers, respectively.

Please note the following: 1) in practice, you as the analyst decide how to assign groups 1 and 2 and subsequently interpret the results appropriately in the context of the data, though for the purposes of this exercise the groups are assigned for you; 2) you might calculate a CI that is different from any of the multiple choice options listed below due to rounding differences, therefore select the closest match; 3) ensure you use either the large or small sample CI formula as appropriate; and 4) you may copy and paste the data into Excel to facilitate analysis. Please show your work

Select one:

a. 15.33 to 20.15 ng/mL

b. 17.73 to 24.79 ng/mL

c. 14.42 to 19.61 ng/mL

d. 16.57 to 21.55 ng/mL

Table 1. Landscapers

Subject

Vitamin D

1

57.686

2

51.967

3

49.892

4

49.761

5

55.567

6

50.879

7

47.504

8

60.187

9

55.417

10

59.426

11

49.321

12

52.711

13

49.728

14

44.477

15

58.806

16

50.352

17

51.826

18

55.156

19

57.163

20

56.196

21

60.730

22

55.848

23

51.274

24

53.214

25

51.183

26

57.115

27

50.508

28

50.585

29

50.262

30

55.569

31

55.968

32

50.904

33

54.175

34

57.145

35

46.218

36

49.722

Table 2. Office Workers

Subject

Vitamin D

1

30.974

2

38.855

3

26.562

4

42.949

5

30.572

6

39.908

7

26.016

8

43.615

9

35.605

10

32.409

11

32.799

12

28.429

13

48.600

14

31.181

15

42.416

16

32.599

17

32.219

18

37.190

19

31.262

20

25.641

21

30.710

22

28.710

23

29.892

24

25.944

25

31.403

26

22.090

27

26.878

28

34.411

29

32.846

30

42.342

31

41.339

32

38.236

33

45.500

34

39.545

35

34.381