Answer :
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
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