Use the applet entitled Confidence Intervals for a Mean (the impact of confidence level) to investigate the situation in Exercise 7.11 further. For this exercise, assume that m = 83.2 is the population LO6 mean and s = 6.4 is the population standard deviation.

a. Using n = 100 and the normal distribution with mean and standard deviation as just given, run the applet one time. How many of the 95% confidence intervals contain the mean? How many would you expect to contain the mean? How many of the 99% confidence intervals contain the mean? How many would you expect to contain the mean?

b. Which confidence level has a greater frequency of intervals that contain the mean? Is this result what you would expect? Explain.

c. Without clearing, run the applet several more times.

What happens to the proportion of 95% confidence intervals that contain the mean as you run the applet more and more? What happens to the proportion of 99% confidence intervals that contain the mean as you run the applet more and more? Interpret these results in terms of the meanings of the 95% confidence interval and the 99% confidence interval.

d. Change the distribution to right skewed, clear, and run the applet several more times. Do you get the same results as in part c? Would you change your answer to part e of Exercise 7.11? Explain.