The table given below provides information about the marks obtained by a group of students in a test.
| Marks | No. of Students |
| Less than 10 | 2 |
| Less than 20 | 5 |
| Less than 30 | 6 |
| Less than 40 | 8 |
| Less than 50 | 10 |
What is total number of students in the group?
1
20
2
10
3
8
4
31