Some pupils took a Math mock test. Their average score was 77.9 marks. One of the pupils' scores was wrongly recorded as 69 marks instead of 96 marks. As a result, the average score was calculated as 76.1 marks. How many pupils sat for the mock test?
| |
If that pupil's score was 96 |
If that pupil's score was 69 |
| Number of pupils |
1 u |
1 u |
| Average score |
77.9 |
76.1 |
| Total score |
77.9 u |
76.1 u |
Difference in the scores due to being wrongly recorded
= 96 - 69
= 27
Difference in total scores of the pupils is due to the difference in the wrongly recorded score.
77.9 u - 76.1 u = 27
1.8 u = 27
1 u = 27 ÷ 1.8 = 15
Number of pupils = 15
Answer(s): 15
