If you count the dots, they are the same for both class (9 people) but the range of the science students' scores are higher than the range for the math students, which means that the sum of their scores will be larger than the math students' and since they have the same number of people, the number being divided for the average would be the same, so the science students' average would be greater than the math's.
31/61 or 50.8 percent the daily passes added together are 31 passes for adults and children. Adding everything together gives us the denominator of the fraction 61. 31/61 = 50.8%.