You are a manager at a firm and you think your monthly costs have increased. The costs have always been $9,000 but you now think they are more and would like to test this claim. If you run hypothesis test, which of following statements would fit your problem?
A. You've an upper tail test
B. Your alternative hypothesis could be stated as population mean is less than 9,000
C. Your null hypothesis could be stated as the population mean is greater than or equal to 9,000.
D. A, B, and C are correct
E. Just B and C are correct