Platies should not be agressive, and it dosent matter what ratio of males/females there are.
i will beg to differ here, in my 3 experiences in owning platies they have been the most agressive community fish i have ever owned other than my bettas, and since then i have never owned one (k i lie, i got a hitchhiker recently with some fish i bought so i have a prego platy, but it wasnt my choice!)
<-ninjaed again lol, thanks maura, but yours shows more detail, finding a good pic of a gonopodium (FISH!) is NOT easy lol, i had to blow up a tiny one to make it look nice->
-edit for typos-you know i would help my case if i learned how to type *sigh*.