Following are scores on a test in the form of ranges, with the corresponding number of students in parentheses: 55–60 (2); 60–65 (4); 65–70 (7); 70–75 (7); 75–80 (1); 80–85 (6); 85–90 (3); 90–95 (3);

95–100 (5). Plot three histograms: (1) cell width of 5; (2) cell width of 10 starting at 50; and (3) cell width of 10 starting at 55. What general observations can be made from a comparison among the three histograms?