Math  /  Data & Statistics

QuestionState whether each of the following changes would make a confidence interval wider or narrower. (Assume that nothing else changes.) a. Changing from a 95%95 \% confidence level to a 90%90 \% confidence level. b. Changing from a sample size of 400 to a sample size of 30 . c. Changing from a standard deviation of 30 pounds to a standard deviation of 15 pounds.
Click the icon to view the tt-table. a. How will changing from a 95%95 \% confidence level to a 90%90 \% confidence level affect the width of the confidence interval? A. The interval will become wider. B. The interval will become narrower. C. This change will not affect the width of the interval.

Studdy Solution
c. Changing from a standard deviation of 30 pounds to a standard deviation of 15 pounds affects the width of the confidence interval. A smaller standard deviation decreases the standard error sn\frac{s}{\sqrt{n}}, which results in a narrower confidence interval.
Conclusion for part (c): B. The interval will become narrower.

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