ECON 153 2. An instructor decided to run two slight variations of the same exam. Prior to passing out the exams, she shuffled the exams together to ensure each student received a random version. Summary statistics for how students performed on these two exams are shown below. Anticipating complaints from students who took Version B, she would like to test whether the difference observed in the groups is so large that it provides convincing evidence that Version B was more difficult (on average) than Version A. Use 0.05 level of significance. Version A B Number of exams 30 27 Sample standard deviation 1) State the null and the alternative hypotheses 2) Identify the rejection region 3) Calculate the value of the test statistic. 4) State your test decision 5) State the test conclusion