The scatter graph shows the number of hours spent revising and the test scores for 12 students.
| Revision (hours) | Test Score (%) |
|---|---|
| 2 | 30 |
| 3 | 38 |
| 5 | 42 |
| 6 | 51 |
| 8 | 55 |
| 9 | 64 |
| 11 | 62 |
| 13 | 75 |
| 14 | 82 |
| 16 | 85 |
| 18 | 91 |
| 20 | 98 |
a.[1]
What type of correlation does the scatter graph show?
b.[2]
Another student revised for 12 hours. Estimate the test score for this student.