300
You want to see if students do better on a test if they study with music. You divide up one class into 2 groups of 15 students. Group A listens to music while studying their notes for 1 hour a night. Group B studies their notes with no music for 1 hour a night. After two weeks, a comprehension test was given to all students after they had studied their notes in silence or with music turned on.
What is 4--two weeks, 1 hour a night, 2 groups of 15 students, test