According to the text the author gives us
A. The width of the walls of the vessel.
B. The height of the vessel.
C. The total volume of the vessel.
D. The diameter of the rim.
The circumference of the body is the only missing variable.
So from this circumstance you conclude that the missing variable was not given and instead the author gave us a second measurement of the rim. You make this conclusion even though the given number would be within the range expected if it were describing the body of the vessel.
You partially justify your conclusion by making fun of the person measuring it even though the easiest and most exact measurement of the rim would be to measure its diameter and the only practical measurement to make of the body is to measure its circumference.
I respectively submit that after looking at the text in its entirety the conclusion that the author gives us two meaurements of the same part of the object is the most contrived conclusion.