I suspect problem needs more clarity - is length and width measured parallel to the paper or indicated by the longest and narrowest diameters of each spot? What rule determines membership of each group? And anyway, what does size mean - shoe size? length? area? volume (if the spots are thick)? And I wonder whose fault is it that the problem is so vaguely expressed. If it's yours, get the proper version, otherwise get a proper teacher.

Update: When changing a post, please use "strike" tags rather than actually deleting and replacing, or just add update like this, otherwise you undermine people's replies.

We still need to know what "group" means in this context. It could be integral square millimetres, quarter inches squared, or in fact anything you like of that sort.