Expand Your Knowledge: Split Stem The Boston Marathon is the oldest and best-known U.S. marathon. It covers a route from Hopkinton, Massachusetts, to downtown Boston. The distance is approximately 26 miles. Visit the Brase/

Brase statistics site at http://www.cengagebrain.com and fi nd the link to the Boston Marathon. Search the marathon site to fi nd a wealth of information about the history of the race. In particular, the site gives the winning times for the Boston Marathon. They are all over 2 hours. The following data are the minutes over 2 hours for the winning male runners:

1961–1980 23 23 18 19 16 17 15 22 13 10 18 15 16 13 9 20 14 10 9 12 1981–2000 9 8 9 10 14 7 11 8 9 8 11 8 9 7 9 9 10 7 9 9

(a) Make a stem-and-leaf display for the minutes over 2 hours of the winning times for the years 1961 to 1980. Use two lines per stem.

(b) Make a stem-and-leaf display for the minutes over 2 hours of the winning times for the years 1981 to 2000. Use two lines per stem.

(c) Interpretation Compare the two distributions. How many times under 15 minutes are in each distribution?