Some pupils took a Math mock test. Their average score was 71.8 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 71.5 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 |
71.8 |
71.5 |
| Total score |
71.8 u |
71.5 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.
71.8 u - 71.5 u = 9
0.3 u = 9
1 u = 9 ÷ 0.3 = 30
Number of pupils = 30
Answer(s): 30
