Previously, an organization reported that teenagers spent 4.5 hours per week, on average, on the phone. The organization thinks that, currently, the mean is higher. Fifteen randomly chosen teenagers were asked how many hours per week they spend on the phone. The sample mean was 4.75 hours with a sample standard deviation of 2.0. In conducting a hypothesis test, the Type I error is (circle the correct answer):

a) to conclude that the current mean hours per week is higher than 4.5, when in fact, it is higher

b) to conclude that the current mean hours per week is higher than 4.5, when in fact, it is the same

c) to conclude that the mean hours per week currently is 4.5, when in fact, it is higher

d) to conclude that the mean hours per week currently is no higher than 4.5, when in fact, it is not higher

8. Previously, an organization reported that teenagers spent 4.5 hours per week, on average, on the phone. The organization thinks that, currently, the mean is higher.

Fifteen randomly chosen teenagers were asked how many hours per week they spend on the phone. The sample mean was 4.75 hours with a sample standard deviation of 2.0. Conduct a hypothesis test. The null and alternative hypotheses are (choose the correct answer): a. H0: x = 4.5, Ha: x > 4.5 b. H0: µ = 4.5, Ha: µ < 4.5 c. H0: µ = 4.75, Ha: µ > 4.75 d. H0: µ = 4.5 Ha: µ > 4.5

Assume that there are 800 Statistics students at UMUC in a given year, and the same Final Exam was administered to all of them. You are interested to know estimate of the population parameters, and a simple random sample of 15 scores was taken from the test results. They are 51, 63, 56, 43, 34, 62, 73, 49, 53, 77, 67, 58, 56, 75, and 65 (these scores are not percentages).

Question 1

Using the Critical Value Method, test the claim that the mean of the population is greater than 55. Take a = 5%. Be neat, orderly, show every step, and sketch plot accordingly.

Question 2

In the sample, 10 out of 15 test scores earned a "C" or higher. Using the P-Value Method, test the claim that the proportion of students in the population that received a "C" or higher was less than 85%. Consider a = 5%. Be neat, orderly, show every step, and sketch plot accordingly.