Council Directive of 20 January 1976 on the approximation of the laws of the Member States relating to the making-up by weight or by volume of certain prepackaged products (76/211/EEC)

2.3. Checking of the average actual contents of the individual prepackages making up a batch U.K.

2.3.1. A batch of prepackages shall be considered acceptable for the purpose of this check if the mean value of the actual contents x_i of n prepackages in a sample is greater than the value: U.K.

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.

2.3.2. If x_i is the measured value for the actual contents of the i-th item in the sample containing n items then: U.K.

2.3.2.1. the mean of the measured values for the sample is obtained by the following calculation: U.K.

2.3.2.2. and the estimated value of the standard deviation s by the following calculation: U.K.

• the sum of the squares of the measured values:

• the square of the sum of the measured values:

  then

• the corrected sum

• the estimated variance:

the estimated value of the standard deviation is:

2.3.3. Criteria for acceptance or rejection of the batch of prepackages for checking the mean: U.K.

2.3.3.1. Criteria for non-destructive testing U.K.

Number in batch	Number in sample	Criteria
		Acceptance	Rejection
100 to 500 (inclusive)	30
> 500	50

2.3.3.2. Criteria for destructive testing U.K.

Number in batch	Number in sample	Criteria
		Acceptance	Rejection
Whatever the number (≥100)	20