There is absolutely zero reason to treat movie rating grades as if they were school rating grades. The two have no connection to one another.
And even if you want to compare them, you wouldn't do it with percentages. A C is "average" not because it's 70%, but because it's in the middle of the five letters: A and B above it, D and F below. It's in the center of the scale. And the center of Mark's scale isn't 7, it's 5.
And even if you want to compare them, you wouldn't do it with percentages. A C is "average" not because it's 70%, but because it's in the middle of the five letters: A and B above it, D and F below. It's in the center of the scale. And the center of Mark's scale isn't 7, it's 5.