Let the number of girls be g and the number of boys be b. b = 3g Class average = class score/class size = 17 17 = (class score) / 3g + g 68g = class score Class score = girls score + boys score Girls average = girls score/g girls score = 18g 68g = 18g + boys score boys score = 50g Boys average = 50g/3g = 16.7
