Answer
a. The claim is supported.
b. The claim is supported.
c. No
Work Step by Step
a. We want to see if the mean change is less than 22.2, so we know $H_0: \mu = 22.2$ and $H_1: \mu<22.2$. We now use a Ti-84 calculator. To solve, go to "Stat," then "Tests," and then select "Stats." Doing this, we 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 find that the confidence interval is all positive, suggesting that more 55 and older people experience black and white dreams, thus supporting the claim.
c. They cannot show that this change results from exposure to the media, for the results in a and b do not prove anything about the causes of the change in dreams.
