The average test score of a class was 66 marks. After five pupils who scored an average marks of 93 marks transferred out of the class, the average score of the remaining pupils became 63 marks. How many pupils were there in the class in the end?
| |
(1) |
(2) |
| Number |
1 u |
1 u - 5 |
| Value |
66 |
63 |
| Total value |
66 u |
63 u - 315 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 66
= 66 u
Total score of the 5 pupils
= 5 x 93
= 465
Total marks scored after 5 pupils transferred out
= 63 x (1 u - 5)
= 63 u - 315
66 u - 465 = 63 u - 315
66 u - 63 u = 465 - 315
3 u = 150
1 u = 150 ÷ 3 = 50
Number of pupils in the class in the end
= 1 u - 5
= 50 - 5
= 45
Answer(s): 45
