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To construct:
Each specified confidence interval and interpret the interval.
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Answer to Problem 20E
Solution:
The confidence interval is
Explanation of Solution
Confidence interval is used to compare two population variances, estimate the value of the ratio or fraction,
1. If the confidence interval contains 1 that means the two population variances are unequal at a particular level of confidence.
2. If both endpoints of the interval are greater than 1 it concludes that
3. If both endpoints of the interval are less than 1 it concludes that
Given Information:
From the given information, Amy’s practice run is
Formula used:
The formula to calculate the confidence interval is,
The formula to calculate the point estimate is,
Where,
For the given level of confidence
The right and left endpoints for
Calculation:
Substitute 2.560 for
At 90% level of confidence or
The right endpoint for
Similarly the left endpoint for
The degrees of freedom are,
And,
The sample sizes are given as
Substitute 16 for
Substitute 15 for
For the column of
For the column of
The formula to calculate the confidence interval is,
Substitute
Thus, the confidence interval is
Interpretation:
Since the value 1 is in the interval
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Chapter 9 Solutions
Beginning Statistics, 2nd Edition
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