Calculating the Most Probable Number of Growth Units

Counts of green grid-cells from 8 rows on the duplicate HGMF are 157 and 164, respectively.

1)	Score for filter 1 (157 x 5) =	785
	Score for filter 2 (164 x 5) =	820
2)	MPNGU of filter 1 =	1079
	MPNGU of filter 2 =	1149
3)	Average MPNGU =	1114
4)	No. of organisms/ml =	1114

Counts of negative (not-green) grid-cells from 8 rows on the duplicate HGMF, inoculated with

1.0 ml, are 57 and 49, respectively.

1)	Score for filter 1 (1600 - (5 x 57)) =	1315
	Score for filter 2 (1600 - (5 x 49)) =	1355
2)	MPNGU for filter 1 =	2760
	MPNGU for filter 2 =	3002
3)	Average MPNGU =	2881
4)	No. of organisms/ml =	2880

Reporting Results

Report average MPNGU as calculated in 9.5.3, rounded-off to two significant figures (e.g., record 2880 as 2900). If the lowest dilution plated shows no green grid-cells, the recorded value will be the lowest average obtainable with a given volume plated onto a given set of replicate HGMF, preceeded by a "less than" (<) sign, e.g., for 1.0 ml and a set of duplicate HGMF (1 ml per HGMF) the value is < 0.5. This figure should be multiplied by the dilution factor of the inoculum on the HGMF.