The authors of the paper from which the data in Exercise 1.27 was extracted suggested that a reasonable probability model for drill lifetime was a lognormal distribution with 4.5 and .8. a. What are the mean value and standard deviation of lifetime? b. What is the probability that lifetime is at most 100? c. What is the probability that lifetime is at least 200? Greater than 200?

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