You have a tiny dataset that contains information on eight students: their age, number of hours they spent preparing to the exam, and their exam grade. Here it is:
+----+---------+-------+--------------+
| | hours | age | exam_grade |
|----+---------+-------+--------------|
| 0 | 10 | 20 | 76 |
| 1 | 15 | 22 | 80 |
| 2 | 16 | 21 | 83 |
| 3 | 18 | 20 | 80 |
| 4 | 12 | 19 | 75 |
| 5 | 11 | 20 | 70 |
| 6 | 17 | 20 | 85 |
| 7 | 12 | 20 | 78 |
+----+---------+-------+--------------+Your task is to calculate and print the correlation matrix. Put your code inside the print() in the last line.
