One subject at KBS suggests that students should study an average of 6 hours per week outside of class time. A student claims that the average time studied is greater than this. She took a random sample of 25 students and found a mean of 6.6 hours with a standard deviation of 1.2 hours per week. You are further told that the value of the calculated test statistic is 2.5. Assume the distribution is normal.

a) Give the null and alternative hypotheses to test the student's claim.

b) Give the critical value if testing at the 5% level of significance.

c) State your decision, giving your reasoning.

d) State your conclusion in the context of this question.