The following data show spot speeds collected at a section

Last updated: 2/8/2023

The following data show spot speeds collected at a section of highway located in a residential area before and after an increase in speed enforcement activities All speeds are in mi h After Before 27 41 31 31 27 40 Before 44 33 40 41 31 32 32 33 37 44 31 37 www 40 34 42 Before mean speed standard deviation 35 36 27 26 26 85th percentile speed percentage exceeding limit 35 22 22 25 26 37 After mean speed standard deviation 85th percentile speed 30 33 34 39 38 32 34 36 27 36 38 29 29 After 201 17 35 33 29 21 31 19 Using the student s t test determine whether there was a statistically significant difference in the average speeds at a significance level of a 0 05 the 95 percent confidence level OYes there was a statistically significant difference in the average speeds O No there was not a statistically significant difference in the average speeds 24 30 Also report for both the before and after cases the mean speed standard deviation 85th percentile speed and percentage of traffic exceeding the posted speed limit of 30 mi h Enter all speeds and standard deviations in mi h Round your 85th percentile speeds to at least the nearest Integer 16 20 33 28 33 mi h mi h mi h mi h mi h mi h