Question

The mean time for fire crews to get to a certain neighborhood has historically been 9.3 minutes. A new fire station was built not far from a certain neighborhood. The residents want to pay less for fire insurance, so they need to prove to the insurance company that the mean time for fire trucks to get to their neighborhood has decreased. They take a sample of 13 times when fire crews had to come to their neighborhood from the new station, and they find it took them an average of 7.8 minutes with a standard deviation of 2.13 minutes. At a 0.005 level of significance, do the residents have enough evidence? (Population is approximately normal.)

1. What is the claim? What are the null and alternate hypotheses? Will it be a one or two tailed test?

2. Do we use z, t, or nothing? Why?

3. Summarize the sample information and then find t* or z*.

4. What is your conclusion?

Answer 1