We're conducting a hypothesis test in which we are trying to determine whether studying before doing the exams to better scores on the exam. Let's say that the population of Stats 157 students has a mean score of 40 and a standard deviation of 4. We take a sample of 4 students and have them do all the chapters before taking their exam. We find that their average score on the exam is 45. What is the probability of obtaining such a sample, and can we reject our null hypothesis assuming our alpha value is set to .05?

Would the probability be

49.38%?

.62%?

99.38%?