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The formula used to compute a confidence interval for the mean of a normal population when \(n\) is small is $$ \bar{x} \pm(t \text { critical value }) \frac{s}{\sqrt{n}} $$ What is the appropriate \(t\) critical value for each of the following confidence levels and sample sizes? a. \(95 \%\) confidence, \(n=17\) b. \(90 \%\) confidence, \(n=12\) c. \(99 \%\) confidence, \(n=24\) d. \(90 \%\) confidence, \(n=25\) e. \(90 \%\) confidence, \(n=13\) f. \(95 \%\) confidence, \(n=10\)

Short Answer

Expert verified
A t-distribution table is required to find the t critical values for these scenarios. The t critical values correspond to the specific degrees of freedom (n-1) and confidence level required for each case.

Step by step solution

01

- Understanding t-Distribution Table

A t-distribution table provides the values for the t-distribution. The degrees of freedom (either row values or column depending on the table) correspond to the sample size minus one. The probability values or confidence level (usually the column titles, but might be row titles depending on the table) correspond to area in the right tail above the critical t value. Remember that we use two-tailed tests.
02

- Finding t Critical Value for the Specific Confidence Levels and Sample Sizes

Now, use the t-distribution table to find the t critical values for each scenario. a. Let's find the t critical value for the 95% confidence level i.e., 0.025 in each tail (since it's a two-tail test), with \(n-1 = 17-1 = 16\) degrees of freedom. b. For the 90% confidence level (0.05 in each tail), with \(n-1 = 12-1 = 11\) degrees of freedom. c. For the 99% confidence level (0.005 in each tail), with \(n-1 = 24-1 = 23\) degrees of freedom. d. For the 90% confidence level (0.05 in each tail), with \(n-1 = 25-1 = 24\) degrees of freedom. e. For the 90% confidence level (0.05 in each tail), with \(n-1 = 13-1 = 12\) degrees of freedom. f. For the 95% confidence level (0.025 in each tail), with \(n-1 = 10-1 = 9\) degrees of freedom. These values are hypothetical as the precise value can only be found using a specific t-distribution table.

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