Question 16 of 39 1 Points A researcher is interested in studying whether changing your daily routine influences test scores. She randomly samples 25 people from a population and computes a mean *= 40 and sampling variance, s?, = 12. She wants to test if & = 40 is statistically significantly different from the population mean = 30, and she does not have the population variance. Which test should she use? A one tailed z-test B. one tailed ttest C. two-tailed z-test D. two-tailed ttest