The average test score of a class was 63 marks. After four pupils who scored an average marks of 94 marks transferred out of the class, the average score of the remaining pupils became 59 marks. How many pupils were there in the class at first?
| |
(1) |
(2) |
| Number |
1 u |
1 u - 4 |
| Value |
63 |
59 |
| Total value |
63 u |
59 u - 236 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 63
= 63 u
Total score of the 4 pupils
= 4 x 94
= 376
Total marks scored after 4 pupils transferred out
= 59 x (1 u - 4)
= 59 u - 236
63 u - 376 = 59 u - 236
63 u - 59 u = 376 - 236
4 u = 140
1 u = 140 ÷ 4 = 35
Number of pupils in the class at first
= 1 u
= 35
Answer(s): 35
