Never claim the true height of a human being by mesuring the length of its feet...it doesn't work !!!
Petrie goofed "BIG TIME".
Actually I have given that a great deal of thought and were there to be a "perfect" geometrically proportioned humanoid male I would suspect the height would be EXACTLY 6 feet (72 inches) and the foot would be EXACTLY JUST THAT 12 inches or a foot, 1/6th of the height.
Geometrical perfection can be found in a humanoid. Did the [real] ancients measure up ?