What is a good 5k time for females?

I ran last year for a couple of months my fastest 5k was 28 minutes. I stopped running for a while because of bad shin splints but now i'm just getting back to running and now my 5k is 42 minutes which is way too slow. I keep having to stop because of my shins hurting. By the way i'm now 16. I wanna get a scholarship for crosscountry what would be a good time I would need for a scholarship?