The table below shows the weights of 9 subjects before and after they followed a
ID: 3376239 • Letter: T
Question
The table below shows the weights of 9 subjects before and after they followed a particular diet for two months.
Subject
A
B
C
D
E
F
G
H
I
Before
168
180
157
132
202
124
190
210
171
After
162
178
145
125
171
126
180
195
163
Construct a 95% confidence interval for the mean difference of the "before" minus "after" weights. Assume that the conditions and assumptions for inference are satisfied.
Subject
A
B
C
D
E
F
G
H
I
Before
168
180
157
132
202
124
190
210
171
After
162
178
145
125
171
126
180
195
163
Explanation / Answer
solution:- option B. (2.7, 17.1)
given that difference of the "before" minus "after" weights are
6,2,12,7,31,-2,10,15,8
mean = 9.9
standard deviation = 9.4
95% confidence with df = 8 is 2.306
confidence interval formula is x +/- t * s / sqrt(n)
=> 9.9 +/- 2.306 * 9.4 / sqrt(9)
=> 9.9 +/- 7.2255
=> (2.7, 17.1)
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