| X | Y | D (X − Y) | D2 (X − Y)2 |
| 7.0 | 6.8 | 0.2 | 0.04 |
| 1.8 | 1.9 | −0.1 | 0.01 |
| 4.2 | 4.5 | −0.3 | 0.09 |
| 0.01 | 0.01 | 0 | 0 |
| 0.01 | 0.03 | 0.02 | 0.0004 |
| 0 | 0 | 0 | 0 |
| 37 | 39 | −2 | 4 |
| X = 7.15 |
|
| ∑4.14 |