Sarah has data about the number of hours 10 students spent revising and the marks they achieved in a test. She was asked to display the data on a scatter graph. Here is her answer.
Sarah's graph shows 'Marks' on the y-axis and 'Hours Spent Revising' on the x-axis. The marks on the y-axis are labelled 0,10,20,30,50,60,70,800, 10, 20, 30, 50, 60, 70, 800,10,20,30,50,60,70,80. She has drawn a straight line of best fit that is horizontal across the graph.
| Hours Spent Revising | Test Mark |
|---|---|
| 2 | 18 |
| 4 | 25 |
| 5 | 32 |
| 8 | 45 |
| 10 | 48 |
| 12 | 60 |
| 15 | 65 |
| 18 | 78 |
| 20 | 82 |
| 22 | 90 |
Sarah has plotted the points accurately.
Write down two things that are wrong with her answer.