Mehh.. If you keep the screen at under half brightness and are working offline (wi-fi and bluetooth off) with non CPU intensive programs, then you could probably squeeze close to that out of it.
However with wifi on and screen at half bright, the timer on mine at full charge says 7 hrs give or take, however, I've never actually timed it for real.
It's a heck of a lot better than the factory battery in my PC laptop which makes me happy. 😎