At my university, many students use tests from previous semesters to study for exams. These old tests are available to about 75 percent of students because fraternities, sororities, and some dorms keep them on file. Is it ethical to use these tests? —L.T., Michigan

ANSWER As long as you’re not using the actual test you’ll be taking, and as long as your professors permit this practice, you’re free to employ these old tests as review material. But while you are meeting your ethical obligations, your professors are not. If they regard these old tests as legitimate study aids, they must make them available to all. What you might do is make sure that your professors are aware of the problem and that they are addressing it.

—Adapted from “The Ethicist” in The New York Times Magazine