Some pupils took a Math exam. Their average score was 75.4 marks. One of the pupils' scores was wrongly recorded as 89 marks instead of 98 marks. As a result, the average score was calculated as 74.9 marks. How many pupils sat for the exam?
|
If that pupil's score was 98 |
If that pupil's score was 89 |
Number of pupils |
1 u |
1 u |
Average score |
75.4 |
74.9 |
Total score |
75.4 u |
74.9 u |
Difference in the scores due to being wrongly recorded
= 98 - 89
= 9
Difference in total scores of the pupils is due to the difference in the wrongly recorded score.
75.4 u - 74.9 u = 9
0.5 u = 9
1 u = 9 ÷ 0.5 = 18
Number of pupils = 18
Answer(s): 18