Mailboxes do not have precise measurements, as they are not produced by the government, in the US, anyway; rather the US Mail sets parameters, max and min measurements, within which post boxes may be produced by the commercial sector. For the correct parameters for a US Mail box, go to mail.gov.
What determines how precise a measurement is
It is precise if it is repeatable.
The measurement 25.81 is precise to the nearest hundredth.
No. Accurate relates to how close the actual measurement the instrument measures. Precise relates to how much detail the instrument gives when measuring. They are independent to each other: An measurement can be precise and accurate (eg the value of π is 3.141592654) An measurement can be precise and inaccurate (eg the value of π is 1.733677432) An measurement can be less precise and accurate (eg the value of π is 3.14) An measurement can be less precise and inaccurate (eg the value of π is 1.73).
measuring tape
An automatically measurement has a higher precision than a manually measurement.
19.2cm is more precise
The precision of a measurement can be determined by looking at the number of decimal places in the measurement. The more decimal places, the more precise the measurement. Additionally, if a measuring tool is capable of measuring smaller increments, it can provide a more precise measurement.
meters
Is as exact as possible
tenth of a gram
They are equally precise.