The DataFrame grades contains the table with student grades:
+----+-----------+-----------+------------+-----------+--------------------+-----------+-----------+
| | Student | Algebra | Geometry | Physics | Computer_science | English | Biology |
|----+-----------+-----------+------------+-----------+--------------------+-----------+-----------|
| 0 | Ann | 10 | 8 | 7 | 10 | 9 | 8 |
| 1 | Bob | 8 | 6 | 3 | 4 | 9 | 9 |
| 2 | Chris | 9 | 9 | 9 | 6 | 9 | 7 |
| 3 | Drake | 3 | 6 | 5 | 7 | 10 | 4 |
| 4 | Emma | 8 | 9 | 4 | 5 | 5 | 5 |
| 5 | Finn | 4 | 4 | 7 | 6 | 8 | 7 |
| 6 | Ginny | 6 | 5 | 10 | 4 | 10 | 3 |
+----+-----------+-----------+------------+-----------+--------------------+-----------+-----------+Create a Series with the mean grade by each student (no grouping/aggregations/reshaping) and print it.
