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t time When constructing confidence intervals for a population mean, we almost always
Chapter 8, Problem R8.10(choose chapter or problem)
t time When constructing confidence intervals for a population mean, we almost always use critical values from a t distribution rather than the standard Normal distribution. (a) When is it necessary to use a t critical value rather than a z critical value when constructing a confidence interval for a population mean? (b) Describe two ways that the t distributions are different from the standard Normal distribution. (c) Explain what happens to the t distributions as the degrees of freedom increase.
Questions & Answers
QUESTION:
t time When constructing confidence intervals for a population mean, we almost always use critical values from a t distribution rather than the standard Normal distribution. (a) When is it necessary to use a t critical value rather than a z critical value when constructing a confidence interval for a population mean? (b) Describe two ways that the t distributions are different from the standard Normal distribution. (c) Explain what happens to the t distributions as the degrees of freedom increase.
ANSWER:Step 1 of 3
(a)
We need to use the critical value instead of a critical value when we don't know the population standard deviation.
Then, we use the sample standard deviation, to estimate the population standard deviation .