Some pupils took a Math exam. Their average score was 79.7 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 79.2 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 |
79.7 |
79.2 |
Total score |
79.7 u |
79.2 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.
79.7 u - 79.2 u = 9
0.5 u = 9
1 u = 9 ÷ 0.5 = 18
Number of pupils = 18
Answer(s): 18