Question 7.14

7.14 Finding critical .

What critical value from Table D should be used to calculate the margin of error for a confidence interval for the mean of the population in each of the following situations?

  1. A 95% confidence interval based on observations.
  2. A 90% confidence interval from an SRS of 27 observations.
  3. A 95% confidence interval from a sample of size 27.
  4. These cases illustrate how the size of the margin of error depends on the confidence level and on the sample size. Summarize the relationships illustrated.