The librarian at the local elementary school claims that, on average, the books in the library are more than 20 years old. To test this claim, a student takes a sample of n = 30 books and records the publication date for each. The sample produces an average age of µ = 23.8 years with a variance of s2 = 67.5.
Use this sample to conduct a one-tailed test with a = .01 to determine whether the average age of the library books is significantly greater than 20 years (m . 20).