What is the mean difference of the two samples?
| Test 1 | Test 2 |
| 46 | 20 |
| 14 | 22 |
| 41 | 24 |
| 16 | 19 |
| 14 | 45 |
| 35 | 39 |
| 16 | 32 |
| 38 | 26 |
| 15 | 48 |
| 19 | 38 |
| 11 | 26 |
| 30 | 50 |
| 39 | 47 |
| 46 | 15 |
| 38 | 22 |
| 43 | 29 |
| 22 | 20 |
| 19 | 11 |
| 36 | 50 |
| 28 | 43 |
| 36 | 46 |
| 19 | 23 |
| 27 | 16 |
| 41 | 21 |
| 33 | 28 |
| 26 | 26 |
| 49 | 41 |
| 14 | 29 |
| 26 | 45 |
| 47 | 27 |
| 19 | 24 |
| 42 | 29 |
| 19 | 24 |
| 50 | 45 |
| 18 | 49 |
| 23 | 21 |
| 44 | 36 |
| 37 | 24 |
| 12 | 26 |
| 45 | 30 |
| 17 | 14 |
| 31 | 24 |
| 42 | 38 |
| 32 | 21 |
| 36 | 18 |
| 35 | 22 |
| 26 | 18 |
| 33 | 29 |
| 13 | 41 |
| 45 | 43 |