Analysts of traffic control systems believe that the average speed of heavy vehicles on highways has decreased after passing an ordinance of high penalty to regulate over speeding. The average speed...

Analysts of traffic control systems believe that the average speed of heavy vehicles on highways has decreased after passing an ordinance of high penalty to regulate over speeding. The average speed for a random selection of 36 trucks was found to be 55 mph with a standard deviation of 5 mph. The speed before the ordinance was passed was an average of up to 57 mph on these highways.


Which of the following statements is true with regard to the sample data providing sufficient evidence to support the analysts' belief at the 5% significance level?

Group of answer choices