You don't need Minitab or Statdisk for this question. Go to the statistical demonstrations page and choose the Confidence Interval Simulation from section 6.2.

Read the Harris Poll® #71, September 15, 2005, at http://www.harrisinteractive.com/harris_poll/index.asp?PID=601

- Choose Stats / Basic Statistics / 1 Proportion
- You have the summarized data
- The number of trials is the sample size, n, for the survey that you found for part b.
- The number of events is the number of successes, x, and represents the number of people who feel that Bush has done a poor job of handling the Katrina Relief. This is NOT the percent of people that you found for part a, but you'll have to take that percent of the total sample size and round it to a whole number to enter here.
- Click on Options
- Make sure the confidence level is set correctly
- Ignore the test proportion (we'll use this in chapter 7)
- Check the box that says "use test and interval based on normal distribution"

- Click OK

The confidence interval will be given in parentheses under the heading "95% CI". You should write it in inequality notation; for example, if Minitab says (0.46234, 0.56725), then you should write 0.46234 < p < 0.56725.

The following example assumes that you were assigned "September". You should replace that with whatever month you were given to work with.

- Visit the National Weather Service's archive page at http://www.crh.noaa.gov/ilx/archive.php.
- Choose the Decatur Arpt box and select the month September 2005
- Record the "AVG SPD" for the Wind from column 10 for each of the days in September 2005. While you're at it, you might as well go ahead and collect the "AVG" for the temperature from column 4 because you'll need it for question 4.
- Click the Back button and choose September 2004
- Record the "AVG SPD" for the Wind from column 10 for each of the days in September 2004.
- Click the Back button and choose September 2003
- Record the "AVG SPD" for the Wind from column 10 for each of the days in September 2003.

- Label the first column as
**wind** - If you happened to gather the temperature data, then label the second column as
**temp** - Enter the data into the appropriate columns

- Choose Stats / Basic Statistics / 1 Sample T
- The samples are in the
**wind**column - Click Options and make sure the confidence level is set correctly
- Click OK

The confidence interval will be given in parentheses under the heading "95% CI". You should write it in inequality notation; for example, if Minitab says (5.62333, 7.31215), then you should write 5.62333 mph < μ < 7.31215 mph.

If you already collected the temperature data for question 3, then you can skip straight to the Confidence Interval section.

The following example assumes that you were assigned "September". You should replace that with whatever month you were given to work with.

- Visit the National Weather Service's archive page at http://www.crh.noaa.gov/ilx/archive.php.
- Choose the Decatur Arpt box and select the month September 2005
- Record the "AVG" for the temperature from column 4.

- Label an empty column as
**temp** - Enter the data into the
**temp**column.

- Choose Stats / Basic Statistics / 1 Sample T
- The samples are in the
**temp**column - Click Options and make sure the confidence level is set correctly
- Click OK

The confidence interval will be given in parentheses under the heading "95% CI". You should write it in inequality notation; for example, if Minitab says (74.3824, 77.6821), then you should write 74.3824 °F < μ < 77.6821 °F.

Visit the Weatherbase at http://www.weatherbase.com/. Do a search for "Decatur, IL" and find the average temperature for your month.