I clearly don't understand how the print preview scale factor works.

My Drawing Preferences are:

* Paper Format: Letter

* Units: Foot

I have a scale symbol

on the drawing which is 10 feet wide.

I'm trying to print at 1 inch on paper is 10 feet (viz. my scale symbol should be 1 inch wide printed).

At preview scale factor of 1:120, the symbol is less than 1 inch wide printed.

At preview scale factor of 1:110, the symbol is more than 1 inch wide printed.

What exactly is this preview scale factor (x:y what is x and what is y)? I don't understand how to set this value to obtain the stated goal.