9.2.6

The British Department of Transportation studied to see if people avoid driving on Friday the 13^th.They did a traffic count on a Friday and then again on a Friday the 13^th at the same two locations ("Friday the 13th," 2013).The data for each location on the two different dates is in table #9.2.6.Estimate the mean difference in traffic count between the 6^th and the 13^th using a 90% level.

Dates 6th 13th

1990, July 139246 138548

1990, July 134012 132908

1991, September 137055 136018

1991, September 133732 131843

1991, December 123552 121641

1991, December 121139 118723

1992, March 128293 125532

1992, March 124631 120249

1992, November 124609 122770

1992, November 117584 117263