The average test score of a class was 64 marks. After four pupils who scored an average marks of 92 marks transferred out of the class, the average score of the remaining pupils became 50 marks. How many pupils were there in the class in the end?
|
(1) |
(2) |
Number |
1 u |
1 u - 4 |
Value |
64 |
50 |
Total value |
64 u |
50 u - 200 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 64
= 64 u
Total score of the 4 pupils
= 4 x 92
= 368
Total marks scored after 4 pupils transferred out
= 50 x (1 u - 4)
= 50 u - 200
64 u - 368 = 50 u - 200
64 u - 50 u = 368 - 200
14 u = 168
1 u = 168 ÷ 14 = 12
Number of pupils in the class in the end
= 1 u - 4
= 12 - 4
= 8
Answer(s): 8