The librarian at the local elementary school claims that, on average, the books in the library aremorethan 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 and average of M = 23.8 years with a variance of s2= 67.5.

a) Given the statement of the librarian, should the student use a one-tailed or two-tailed test? Why?