Question: A researcher hypothesizes that people who listen to music via headphones have greater hearing loss and will thus score lower on a hearing test than those in the general population. On a standard hearing test, the overall mean for the general population is 22.5. The researcher gives this same test to a random sample of 12 individuals who regularly use headphones. Their scores on the test are 15, 14, 20, 20, 25, 22, 21, 19, 16, 17, 21, 22.

a. What statistical test should be used to analyze the data?

b. Is this a one- or two- tailed test?

c. What are H₀ and H_a for this study?

d. Compute t _obt

e. Should H₀ be rejected? What should the researcher conclude?