Concept explainers
(a)
To find: The two sample standard deviations.
(a)
Answer to Problem 21.26E
The two sample standard deviations are 0.25 and 0.15.
Explanation of Solution
Given info:
In the given information,
Calculation:
The sample standard deviation for alcohol is,
The sample standard deviation for placebo is,
Thus, the two sample standard deviations are 0.25 and 0.15.
(b)
To find: The degrees of freedom by using conservative Option 2 for two-sample t procedures.
(b)
Answer to Problem 21.26E
The degrees of freedom are 24.
Explanation of Solution
Calculation:
The degrees of freedom for the two-sample t procedures with the conservative Option 2 is,
Thus, the degrees of freedom are 24.
(c)
To find: The 90% confidence interval for the mean difference between the two groups.
(c)
Answer to Problem 21.26E
The 90% confidence interval for the mean difference between the two groups is
Explanation of Solution
Calculation:
Critical value:
From the table of “t Distribution critical values”, the critical value for 24 degrees of freedom with 90% confidence level is 1.711.
Confidence interval:
The 90% confidence interval for the mean difference between the two groups is,
Thus, the 90% confidence interval for the mean difference between the two groups is
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Chapter 21 Solutions
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