Find the critical t-value for constructing a confidence interval for a population mean at the given level of confidence for the given
- a. 99% confidence; n = 18
- b. 90% confidence; n = 27
a.
Answer to Problem 1RE
The critical value is 2.898.
Explanation of Solution
Calculation:
Critical value:
For 99% confidence level
The degrees of freedom is,
From Table VII of the t distribution in Appendix A, the critical value that corresponds to the 17 degrees of freedom and 0.005 area in right tail is 2.898.
Thus, the critical value is 2.898.
b.
Answer to Problem 1RE
The critical value is 1.706
Explanation of Solution
Calculation:
Critical value:
For 90% confidence level
The degrees of freedom is,
From Table VII of the t distribution in Appendix A, the critical value that corresponds to the 26 degrees of freedom and 0.05 area in right tail is 1.706.
Thus, the critical value is 1.706.
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