It depends, also, on the subject area. Unlike the hard sciences or mathematics where there is a "right" answer, and an objective method can demonstrate how you arrive at it, writing in the humanities (and to a lesser extent the social sciences) can involve subjective assessments about, for examply, the sufficiency of your research and the clarity of your writing.
When I was an undergraduate, a 70 average put a student on the Dean's List. An 80 average would earn you a degree with distinction. The simple reality was that my undergraduate school did not engage in the type of grade inflation that appears to be prevalent in secondary schools today.
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--James