A class line plot shows the homework times in hours. Each X is one data value. The plot shows: 1/4 has 2 Xs; 1/2 has 1 X; 1 has 1 X; 1 1/4 has 1 X; 1 1/2 has 2 Xs. The totals for 1 and 1 1/2 and 1/4 and 1/2 are compared. What is the positive difference?