The average test score of a class was 69 marks. After five pupils who scored an average marks of 96 marks transferred out of the class, the average score of the remaining pupils became 54 marks. How many pupils were there in the class in the end?
| |
(1) |
(2) |
| Number |
1 u |
1 u - 5 |
| Value |
69 |
54 |
| Total value |
69 u |
54 u - 270 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 69
= 69 u
Total score of the 5 pupils
= 5 x 96
= 480
Total marks scored after 5 pupils transferred out
= 54 x (1 u - 5)
= 54 u - 270
69 u - 480 = 54 u - 270
69 u - 54 u = 480 - 270
15 u = 210
1 u = 210 ÷ 15 = 14
Number of pupils in the class in the end
= 1 u - 5
= 14 - 5
= 9
Answer(s): 9
