So this film was aimed at....

Well, I say 'possibly' because it's based on a YA novel. The core audience for YA novels is typically within an age range of about 12-18. So 11-15 is perhaps a little too narrow an age range for the film. I'd imagine that's not far off the intended core demographic though.

Also, I have no idea if it was aimed specifically at girls. I can well imagine it would appeal more to girls within that age range than boys within that age range. And I'd further imagine the filmmakers were aware of that. But whether that was the aim or not, is a different matter.

I'd imagine the aim was to make it appeal as widely as possible while understanding who its core audience was likely to be.

Yeah I loved Battle Royale. Apparently there's four films in the Hunger Games "trilogy" (part 3 was split into two) so that's an extra one I dodged.