Question 301787
 The critical value Zc that corresponds to a 90% confidence level is:
The critical value Zc that corresponds to a 95% confidence level is:
The critical value Zc that corresponds to a 99% confidence level is:
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Confidence intervals don't really have critical values;
hypothesis tests do.
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But, if you want the z-value associated with 95% 
confidence, the answer is 1.96.
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And the z-value associated with 99% confidence,
the answer is 2.5758
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Cheers,
Stan H.