| . |
| x |
| 5+4+3+2+1 |
| 5 |
| . |
| y |
| 2+1.5+1+1+0.5 |
| 5 |
∴b=
| 5×2+4×1.5+3+2+0.5−5×3×1.2 |
| 52+42+32+22+12−5×32 |
a=1.2-0.35×3=0.15，
∴线性回归方程为y=0.35x+0.15．
故选：A．
| x | 5 | 4 | 3 | 2 | 1 |
| y | 2 | 1.5 | 1 | 1 | 0.5 |
 |
| y |
|
| y |
|
| y |
|
| y |
| . |
| x |
| 5+4+3+2+1 |
| 5 |
| . |
| y |
| 2+1.5+1+1+0.5 |
| 5 |
| 5×2+4×1.5+3+2+0.5−5×3×1.2 |
| 52+42+32+22+12−5×32 |