Most of the time Type A and Type B uncertainties must be combined so that:
that is to say
with
Since only one measurement is performed, urép=0 hence :
An electric current is measured just once with an ammeter with a standard uncertainty of 2.9 mA. Previous measurement results have given a standard uncertainty of 5.2 mA
The standard uncertainty on the value of the measured intensity I is :
In this case the repeatability uncertainty is evaluated from the N replicate measurements.
The same measurement of current is performed 9 times with an ammeter with a standard uncertainty of 2.9 mA.
No other information is given or available.
The standard uncertainty on the value of the measured intensity I is :