(I)在坐标系中描出点, (2,7),(3,8),(5,9),(6,12),散点图如图: (II) ==4,==9, ∴n••=4×4×9=144,4 |
| i=1 | xiyi=14+24+45+72=155,
4 |
| i=1 | x=4+9+25+36=74,n 2=4×16=64,从而有:
| =n |
| i=1 | x iyi-n | n |
| i=1 | x-n | ==1.1 | =-=9-1.1×4=4.6 |
| |
∴
| y | =1.1x+4.6. 故回归方程为
| y | =1.1x+4.6. (III)当x=9时,
| y | =1.1×9+4.6=14.5千元. 答:根据回归方程,销售量为9吨时,销售收入约为14.5千元. |