A batch of prepackages shall be considered acceptable for the purpose of this check if the mean value $x^{-}=\frac{\sum x_i}{n}$ of the actual contents x_i of n prepackages in a sample is greater than the value:

Qn−sn×t1−α

In this formula:

Q_n

the nominal quantity of the prepackage,

n

the number of prepackages in the sample for this check,

s

the estimated standard deviation of the actual contents of the batch,

t_{(1 — α)}

0.995 confidence level of a Student distribution with ν = n — 1 degree of freedom.