Some pupils took a Math mock exam. Their average score was 78.8 marks. One of the pupils' scores was wrongly recorded as 69 marks instead of 96 marks. As a result, the average score was calculated as 77.3 marks. How many pupils sat for the mock exam?
|
If that pupil's score was 96 |
If that pupil's score was 69 |
Number of pupils |
1 u |
1 u |
Average score |
78.8 |
77.3 |
Total score |
78.8 u |
77.3 u |
Difference in the scores due to being wrongly recorded
= 96 - 69
= 27
Difference in total scores of the pupils is due to the difference in the wrongly recorded score.
78.8 u - 77.3 u = 27
1.5 u = 27
1 u = 27 ÷ 1.5 = 18
Number of pupils = 18
Answer(s): 18