MathSnack is a program designed to help small children to learn math more effectively, by playing games on the computer, which requires knowledge of math. To evaluate if the program is effective, 50 students with similar background are randomly selected, and 25 of them are introduced to MathSnack games, while the rest stay in their traditional learning environment. After 2 months, all 50 students are tested and their scores summarize as below. Groups Mean STD Min Max MS 84 4.6 67 96 Trad 76 4.3 56 93 Diff = MS - Trad 8 3.8 -1 12 What is the appropriate inference procedure we need to use here?