Three different sections of the same Interstate highway, with roughly equal traffic volumes, have been patrolled by the State Police at different levels of intensity for the past six months. The posted speed limit is 55 and the speeds of random samples of motorists have been registered for each of the three sections. Are the differences in the average speed among the three highway sections (statistically) significant? Was more intensive patrolling effective?

Descriptives Speed 95% Confidence Interval for Mean N Mean Std. Deviation Std. Error Lower Bound Upper Bound Minimum Maximum Lightly Patrolled 8 60.50 8.018 2.835 53.80 67.20 48 72 Moderately Patrolled 8 56.75 1.832 .648 55.22 58.28 54 59 Heavilly Patrolled 54.25 3.454 1.221 51.36 57.14 50 60 Total 24 57.17 5.577 1. 138 54.81 59.52 48 72 ANOVA Speed Sum of Squares df Mean Square F Sig. Between Groups 158.333 2 .072 Within Groups 557.000 21 Total 715.333 23