1. A researcher wants to evaluate the learning ability of college students with various background sounds during learning. She randomly divides 21 participants into three groups. All students study a passage of text for 30 minutes. Those in group 1 study with background sound at a constant volume in the background. Those in group 2 study with background sound that changes volume randomly. Those in group 3 study with no sound at all. After studying, all students take a 10-point multiple choice test about the material. Their scores follow: Constant sound Random sound No sound 7 5 5 4 5 6 6 3 7 8 4 LO 6 4 8 6 6 7 9 6