Question

Set up the null and alternative hypothesis, find the test statistic, reject or fail to reject the null hypothesis, and write a conclusion based off of your results.
According to the American Community Survey, the mean travel time to work in Collin County, Texas , in 2008 was 27.3 minutes. The Department of Transportation reprogrammed all the traffic lights in Collin County in an attempt to reduce travel time. To determine if there is evidence that travel time has decreased as a result of the reprogramming, the Department of Transportation obtains a random sample of 2500 commuters,

Answer 1

records their travel time to work, and finds a sample mean of 27.0 minutes with a standard deviation of 8.5 mins. Does this result suggest that travel time has decreased at the 5% level of significance?

Answer 2

To get you started
the null hypothesis is that the population mean time is 27.3 minutes

Answer 3

okay so you donn't reject the null hypothesis because the p value is bigger than alpha right? but how do i get the alternative hypothesis?

Answer 4

well, we want to test if travel time has decreased

null is: mean <= 27.3
the alt is whats left over, mean > 27.3

or how ever you want to arrange it generally we want alpha error to be as small as possible, the rejection of a true hypot error

Answer 5

i spose, nulll is stays the same or increases

Ho >= 27.3
Ha < 27.3

that seems reasonable