The dot plots below show the test scores of seventh- and eighth-grade students: Dot plot for Grade 7 shows 4 dots on score 60, 6 dots on score 70, 4 dots on score 80 and 6 dots on score 90. Dot plot for Grade 8 shows 5 dots on score 50, 7 dots on score 60, 4 dots on score 70, and 4 dots on score 80. Based on visual inspection of the dot plots, which grade, if any, appears to have the higher mean score? Grade 7 Grade 8 Both groups show about the same mean score. No conclusion about mean score can be made from the data.