Answer:
The 99% confidence interval for the mean commute time of all commuters in Washington D.C. area is (22.35, 33.59).
Step-by-step explanation:
The (1 - <em>α</em>) % confidence interval for population mean (<em>μ</em>) is:
Here the population standard deviation (σ) is not provided. So the confidence interval would be computed using the <em>t</em>-distribution.
The (1 - <em>α</em>) % confidence interval for population mean (<em>μ</em>) using the <em>t</em>-distribution is:
Given:
*Use the <em>t</em>-table for the critical value.
Compute the 99% confidence interval as follows:
Thus, the 99% confidence interval for the mean commute time of all commuters in Washington D.C. area is (22.35, 33.59).