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.

Table #9.2.6: Traffic Count

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