The average test score of a class was 56 marks. After three pupils who scored an average marks of 98 marks transferred out of the class, the average score of the remaining pupils became 50 marks. How many pupils were there in the class at first?
| |
(1) |
(2) |
| Number |
1 u |
1 u - 3 |
| Value |
56 |
50 |
| Total value |
56 u |
50 u - 150 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 56
= 56 u
Total score of the 3 pupils
= 3 x 98
= 294
Total marks scored after 3 pupils transferred out
= 50 x (1 u - 3)
= 50 u - 150
56 u - 294 = 50 u - 150
56 u - 50 u = 294 - 150
6 u = 144
1 u = 144 ÷ 6 = 24
Number of pupils in the class at first
= 1 u
= 24
Answer(s): 24
