A professor was curious about her students' grade point averages (GPAs). She took a random sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of the following formulas gives a 99% confidence interval for the mean GPA of the professor's students?
A) 3.01 +- 2.977(0.534/root 15)
B) 3.01+-2.97(0.534/root 14)
C) 3.01+-2.947(0.534/root 15)
D) 3.01+-2.947(0.534/root14)
E) 3.01+-2.576(0.534/root 15)
Answer: A