Some pupils took a Math mock exam. Their average score was 75.7 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 75.5 marks. How many pupils sat for the mock exam?
| |
If that pupil's score was 87 |
If that pupil's score was 78 |
| Number of pupils |
1 u |
1 u |
| Average score |
75.7 |
75.5 |
| Total score |
75.7 u |
75.5 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.
75.7 u - 75.5 u = 9
0.2 u = 9
1 u = 9 ÷ 0.2 = 45
Number of pupils = 45
Answer(s): 45
