A statistics teacher is interested in studying the change in test-taking ability on student's second exam compared to their first exam. The professor decides to run the experiment with 20 students. Their findings show that 18 of 20 students performed better on the second exam compared to their scores on the first exam. Conduct a sign test using an alpha of 0.05.

a.What is the null hypothesis?

b.What is the alternative hypothesis?

c.What is the critical value? (Hint: there should be two)

d.Calculate the p value.

e. What is your decision? (Circle one): Reject or Fail to reject

f.What do these results mean in the context of the study? I have the answer, but can you please elaborate how you get a critical value of +/-9