Students who graduated from college last year owed an average of $25,250 in student loans. An economist wants to determine if average debt has changed. She takes a sample of 40 recent graduates and finds that their average debt is $27,500 with a standard deviation of $9,120. Use 90% confidence interval. Which of the following conclusion is correct?
A. The average debt has not changed.
B. The average debt increased.
C. The average debt decreased.
D. There is not enough information.