=+3.44 ● Some days of the week are more dangerous than others, according to Traffic Safety Facts produced by the National Highway Traffic Safety Administration. Average number of fatalities per day for each day of the week are shown in the accompanying table.

Good time Bad time 53%

67%

78% 78%

29%

25%

19% 20%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Mar-78 Mar-91 Jun-03 Sep-03 122 C h a p t e r 3 ■ Graphical Methods for Describing Data