An advertisement for a popular weight loss clinic suggests that participants in its new diet program lose, on average, more than 10 pounds. A consumer activist decides to test the authenticity of the claim. She follows the progress of 18 women who recently joined the weight reduction program. She calculates the mean weight loss of these participants as 10.8 pounds with a standard deviation of 2.4 pounds.

a. Set up the competing hypotheses to test the advertisement’s claim.

b. At the 5% significance level, specify the critical value(s). What is the decision rule?

c. Calculate the value of the test statistic.

d. What does the consumer activist conclude?