. A lecturer wants to see if a PowerPoint presentation will change students' understanding of a certain concept in Statistics. Five students were randomly selected for the study and were given a pre-test on their understanding of the statistical concept. Then, the students viewed the PowerPoint presentation and afterwards were given a post-test on their understanding of the statistical concept. The data are shown in the table below: Student 1 2 3 4 5 Pre-test score 22 18 20 20 25 Post-test score 35 18 18 41 35 Test at a 5% level of significance whether the PowerPoint presentation makes a difference in the average understanding of the statistical concept. Assume that samples are drawn from a normal population.