I don't really know for sure,but maybe 10.I'm just guessing.

Not sure...

Pinkie was originally depicted as having her own room in the house of employers, and did not have a house of her own like Twilight Sparkle, Rarity, Fluttershy and (possibly) Rainbow Dash) The Cakes treat her like a surrogate daughter. She gets along with most schoolgirls in Ponyville (even gaining a recommendation by Diamond Tiara), and Queen Chrysalis (not-so-subtly) compared Pinkie's taste in parties to that of a small kid. I think Pinkie is a seen as a teenager or young adult, and not as fully adult by the people she interacts with.

she'd probably be a teenager she seems young but not young enough to be a little kid or old enough to be an adult so that's what I think