An hour 20 i think. haven't actually done the trip of a morning yet. Although I'll be used to it, as I travelled that much to get to school everyday...
Our teacher once told us about the time he got lost in ikea, and couldn't get out for an hour. Every lesson after that someone would bring it up, and he'd get really angry. His fault for telling us.
but seriously, my sisters getting like 80's in her course, and she's mildly retarded(well the doctor never picked up on it). so if you study etc, 70 sounds easy enough.