In Exercise 9.17, suppose that the populations are normally distributed with 2 1 = 2 2 = 2. Show that n i=1(Xi X)2 + n i=1(Yi Y )2 2n 2 is a consistent estimator of 2.

Chapter 3 --- Displaying and Describing Quantitative Data The graphical methods used to display quantitative data in this chapter include histograms, stem-and-leaf plots, boxplots, and time series plots. Most of you have seen these types of graphs before and the text gives several examples. That should be enough to refresh your memory of these graphs. We will be using JMP to display these graphs. I will be giving severalexamples in these notes. In class I will point out the advantages and disadvantages of eachgraphicalmethod. The shape of the distribution is important throughout the course. Is the distribution approximately symmetric or skewed to the right or skewed to the left Detecting unusual features (outliers, gaps, clusters) and what to do about them is another important aspect