1. The problem states that the effective number (l'effectif) is 206. 2. "L'effectif" typically refers to the total count or frequency in a data set. 3. Since the problem only provides the total effective number as 206, no further calculations are needed. 4. This means the total number of elements or individuals counted is $206$. 5. If you need to find proportions, percentages, or other statistics, please provide more data.