The winning times of the men’s 400-meter freestyle swimming in the Olympics (1964 to 2008) appear in the following table.

Winning Times in Minutes and Seconds Year Time 1964 4:12.2 1968 4:09.0 1972 4:00.27 1976 3:51.93 1980 3:51.31 1984 3:51.23 1988 3:46.95 1992 3:45.00 1996 3:47.97 2000 3:40.59 2004 3:43.10 2008 3:41.86

(a) Draw a dot diagram and label the points according to time order.

(b) Explain why it is not reasonable to group the data into a frequency distribution.