A teacher at a small university is trying to determine if students learn better when the teacher writes lecture notes on the board or when the teacher uses electronic slides for lecture notes. (Assume the students are not given any note outlines to use, so they start with blank pieces of paper to take notes in both situations). The teacher is going to determine if there is a difference in the mean final test grades for the two different methods. The teacher randomly selects 20 final test grades for those that were taught by writing lecture notes on the board and randomly selects 21 final test grades for those that were taught by using electronic slides for lecture notes.

If a 95% confidence interval estimate for was found to be (-9.8, 2.3) which of the following statements could be made? (Note: =population mean final test grade for those where lectures notes were written on the board. = population mean test exam grade for those where lecture notes were on electronic slides.)