The number of students in a class who have answered correctly, incorrectly, or not attempted each question in an examination is shown in the table below. The marks for each question are also listed. There is no negative or partial marking.
| Q no. | Marks | Answered Correctly | Answered Incorrectly | Not Attempt |
| 1 | 1 | 20 | 10 | 10 |
| 2 | 2 | 15 | 15 | 10 |
| 3 | 5 | 20 | 20 | 0 |
| 4 | 10 | 12 | 15 | 13 |
Find the average of the marks obtained by the class in the examination if the total number of students are 40.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 6.75
Total number of students = 40
Total marks obtained = (1 × 20) + (2 × 15) + (5 × 20) + (10 × 12) = 20 + 30 + 100 + 120 = 270
Average = 270/40 = 27/4 = 6.75
Therefore, the average of the marks obtained by the class in the examination is 6.75.