Listed below are the weight gains for 29 anorexic girls who received cognitive b
ID: 3434098 • Letter: L
Question
Listed below are the weight gains for 29 anorexic girls who received cognitive behavioral therapy. Calculate the 95% confidence interval around the mean.
ID
Gain
ID
Gain
ID
Gain
ID
Gain
ID
Gain
1
1.7
7
3.5
13
1.1
19
1.4
25
1.9
2
0.7
8
17.1
14
-4.0
20
-0.3
26
3.9
3
-0.1
9
-7.6
15
20.9
21
-3.7
27
0.1
4
-0.7
10
1.6
16
-9.1
22
-0.8
28
15.4
5
-3.5
11
11.7
17
2.1
23
2.4
29
-0.7
6
14.9
12
6.1
18
-1.4
24
12.6
ID
Gain
ID
Gain
ID
Gain
ID
Gain
ID
Gain
1
1.7
7
3.5
13
1.1
19
1.4
25
1.9
2
0.7
8
17.1
14
-4.0
20
-0.3
26
3.9
3
-0.1
9
-7.6
15
20.9
21
-3.7
27
0.1
4
-0.7
10
1.6
16
-9.1
22
-0.8
28
15.4
5
-3.5
11
11.7
17
2.1
23
2.4
29
-0.7
6
14.9
12
6.1
18
-1.4
24
12.6
Explanation / Answer
The degree of freedom =n-1=29-1=28
Given a=1-0.95=0.05, t(0.025, df=28) =2.05 (from student t table)
So the lower bound is
xbar - t*s/vn =3.007 - 2.05*7.309/sqrt(29) =0.2246432
So the upper bound is
xbar + t*s/vn= 3.007 + 2.05*7.309/sqrt(29) =5.789357
count 29 mean 3.007 sample variance 53.414 sample standard deviation 7.309Related Questions
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