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. The Boston Marathon web site has 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 over two periods of 20 years each:

Earlier Period 23 23 18 19 16 17 15 22 13 10 18 15 16 13 9 20 14 10 9 12 Recent Period 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 earlier period. Use two lines per stem.

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

(c) Interpretation Compare the two distributions.
How many times under 15 minutes are in each distribution?AppendixLO1