The average test score of a class was 64 marks. After five 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 - 5 |
| Value |
64 |
50 |
| Total value |
64 u |
50 u - 250 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 64
= 64 u
Total score of the 5 pupils
= 5 x 92
= 460
Total marks scored after 5 pupils transferred out
= 50 x (1 u - 5)
= 50 u - 250
64 u - 460 = 50 u - 250
64 u - 50 u = 460 - 250
14 u = 210
1 u = 210 ÷ 14 = 15
Number of pupils in the class in the end
= 1 u - 5
= 15 - 5
= 10
Answer(s): 10
