每件产品的利润 (元)与月份 (月)的关系如下表:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 10 | 10 |