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. -23.72 to -18.19 ng/mL
b. -26.36 to -20.67 ng/mL
c. -22.67 to -17.36 ng/mL
d. -29.65 to -22.01 ng/mL
Table 1. Landscapers
Subject
Vitamin D
1
26.081
2
39.327
3
27.433
4
29.351
5
28.820
6
36.658
7
25.308
8
32.663
9
30.907
10
34.951
11
32.404
12
32.811
13
25.799

Table 2. Office Workers
Subject
Vitamin D
1
52.268
2
50.449
3
57.858
4
53.334
5
53.617
6
56.057
7
50.353
8
53.507
9
55.658
10
61.647
11
55.994
12
56.096
13
52.433
14
48.332
15
56.744
16
57.887
17
48.348
18
59.141
19
54.918
20
58.018
21
56.305
22
50.713
23
53.239
24
59.396
25
47.738
26
62.335
27
48.427