The average test score of a class was 60 marks. After four pupils who scored an average marks of 95 marks transferred out of the class, the average score of the remaining pupils became 56 marks. How many pupils were there in the class in the end?
| |
(1) |
(2) |
| Number |
1 u |
1 u - 4 |
| Value |
60 |
56 |
| Total value |
60 u |
56 u - 224 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 60
= 60 u
Total score of the 4 pupils
= 4 x 95
= 380
Total marks scored after 4 pupils transferred out
= 56 x (1 u - 4)
= 56 u - 224
60 u - 380 = 56 u - 224
60 u - 56 u = 380 - 224
4 u = 156
1 u = 156 ÷ 4 = 39
Number of pupils in the class in the end
= 1 u - 4
= 39 - 4
= 35
Answer(s): 35
