The time needed for all college students to complete a certain paper-and-pencil maze follows a normal distribution with a population mean of 30 seconds and a population standard deviation of 3 seconds.
You wish to see if the mean time μ (where μ stands for population mean) is changed by vigorous exercise, so you have a group of nine college students exercise vigorously for 30 minutes and then complete the maze. It takes them an sample average of 31.2 seconds to complete the maze. Use this information to test the hypotheses:
H0: μ = 30,
Ha: ≠30
at the significance level of 0.01.
You conclude:

a) There is not enough evidence to support the claim.
b) There is enough evidence to support the claim.