A residential area of 20 hectares is planned for three different types of plots of 500 m², 300 m² and 200 m² with numbers of plot in each category are 100, 120, 150 respectively. The rest of the area is allowed for roads and facilities such as school, shops and par ks. Each plot has one dwelling unit and the average household size is 5 persons. The net residential density of the area in person per hectare is ______.