Some pupils took a Math mock test. Their average score was 72.3 marks. One of the pupils' scores was wrongly recorded as 78 marks instead of 87 marks. As a result, the average score was calculated as 72.1 marks. How many pupils sat for the mock test?
| |
If that pupil's score was 87 |
If that pupil's score was 78 |
| Number of pupils |
1 u |
1 u |
| Average score |
72.3 |
72.1 |
| Total score |
72.3 u |
72.1 u |
Difference in the scores due to being wrongly recorded
= 87 - 78
= 9
Difference in total scores of the pupils is due to the difference in the wrongly recorded score.
72.3 u - 72.1 u = 9
0.2 u = 9
1 u = 9 ÷ 0.2 = 45
Number of pupils = 45
Answer(s): 45
