某家电企业在全国二线城市的年销售量Y(单位：万台)与该城市人口数X1(单位:万人)以及该市人均月收入X2(单位:元)之间的关系，在某年对15个城市作了调查，得上述各量的观测值（见数据表data1.txt）-A household electrical appliance enterprises in the country in sales of second-tier cities, Y (unit: million units) and the urban population, the number of X1 (unit: million) and the city' s per capita monthly income X2 (unit: yuan) between, in a particular year made a survey of 15 cities, was the amount of the above observations (see data sheet data1.txt)