Elementary Statistics (12th Edition)

a) We want to see if the mean change is less than $22.2$, so we know $H_0:μ=22.2$ and $H_1:μ\lt22.2$. 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 is $2.33$. Using a z-table calculator, we find that p is $0.000$, meaning that the test hypothesis is supported. b) We use a ti-84 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, suggesting that more 55 and older people experience black and white dreams, hence supporting the claim. c) They cannot show that this change results from exposure to the media, because the results in part a) and part b) do not prove anything about the causes of the change in dreams.