The U.S. Department of Education reports that about 50% of all college students use a student loan to help cover college expenses (National Center for Educational Studies, January 2006). A sample of students who graduated with student loan debt is shown here.

The data, in thousands of dollars, show typical amounts of debt upon graduation.

10.1 14.8 5.0 10.2 12.4 12.2 2.0 11.5 17.8 4.0

a. For those students who use a student loan, what is the mean loan debt upon graduation?

b. What is the variance? Standard deviation?