By utilitiarian you mean:
Caring about all people equally
Hedonism, i.e. caring about pleasure/pain
Both of the above (=Bentham's classical utilitarianism)?
In any case, what answer do you expect? What would constitute a valid reason? What are the assumptions from which you want to derive this?
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.