Select highest dilution that gives positive results in all five portions tested (no lower dilution giving any negative results) and the two next succeeding higher dilutions (Example a). If the lowest dilution tested has less than five portions with positive results, select it and the two next succeeding higher dilutions (Examples b, c).
When positive result occurs in a dilution higher than three selected according to the foregoing rules, change the selection to the lowest dilution that has less than five positive results and the next two higher dilutions (Example d). When all the foregoing selection rules have left unselected any higher dilutions with positive results, add those higher-dilution positive results to the results for the highest selected dilution (Example e). If there were not enough higher dilutions tested to select three dilutions, then select the next lower dilution (Example f)