The Internet site www.artofstat.com/

webapps.html has useful applets for illustrating data analyses and properties of statistical methods.

(a) Using the Explore Quantitative Data applet, construct a sample of 20 observations on y = number of hours of physical exercise in the past week having ¯y < s. What aspect of the shape of the distribution causes this to happen?

(b) Using the Explore Linear Regression applet with the Draw Own option, create 20 data points that are plausible for x = number of hours of exercise last week and y = number of hours of exercise this week. (Note that you can adjust the ranges of the axes in the applet.) Describe your data by the correlation and by the linear regression line, and interpret them.