At a school activity fair, students signed up for either the robotics club or the art club. The table shows the results.
| Grade level | Robotics club | Art club |
|---|---|---|
| 8 | 15 | 10 |
| 9 | 25 | 20 |
One student in grade 8 is selected at random. What is the probability that the selected student signed up for the robotics club?