The average test score of a class was 62 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 54 marks. How many pupils were there in the class at first?
|
(1) |
(2) |
Number |
1 u |
1 u - 4 |
Value |
62 |
54 |
Total value |
62 u |
54 u - 216 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 62
= 62 u
Total score of the 4 pupils
= 4 x 92
= 368
Total marks scored after 4 pupils transferred out
= 54 x (1 u - 4)
= 54 u - 216
62 u - 368 = 54 u - 216
62 u - 54 u = 368 - 216
8 u = 152
1 u = 152 ÷ 8 = 19
Number of pupils in the class at first
= 1 u
= 19
Answer(s): 19