The average test score of a class was 67 marks. After four pupils who scored an average marks of 93 marks transferred out of the class, the average score of the remaining pupils became 65 marks. How many pupils were there in the class in the end?
|
(1) |
(2) |
Number |
1 u |
1 u - 4 |
Value |
67 |
65 |
Total value |
67 u |
65 u - 260 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 67
= 67 u
Total score of the 4 pupils
= 4 x 93
= 372
Total marks scored after 4 pupils transferred out
= 65 x (1 u - 4)
= 65 u - 260
67 u - 372 = 65 u - 260
67 u - 65 u = 372 - 260
2 u = 112
1 u = 112 ÷ 2 = 56
Number of pupils in the class in the end
= 1 u - 4
= 56 - 4
= 52
Answer(s): 52