Answer
a) The claim is supported.
b) The claim is supported.
c) Wearing a seat belt lowers fatality rate.
Work Step by Step
a) We want to see if the mean is different to $\frac{31}{2823}=0.0110$, so we know $H_0:μ=0.0110$ and $H1:μ\lt0.0110$. We now use a Ti-84 calculator. To solve, go to "Stat," then "Tests," and then select "Stats." Doing this, we can find that the critical value and use a z-table calculator to find that $p=0.0000$, so the claim is supported.
b) We use a ti-84 calculator to find the confidence interval. To do this, we press “Stat” and then select “Tests.” Next, we select “2-PropZInt” to conduct the test. Doing this, we can find that the confidence interval is all positive, meaning that wearing a seat belt lowers fatality rate.
c) The results show that wearing a seat belt lowers fatality rate.
