The average test score of a class was 56 marks. After four 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 - 4 |
Value |
56 |
50 |
Total value |
56 u |
50 u - 200 |
Number of pupils at first = 1 u
Total score at first
= 1 u x 56
= 56 u
Total score of the 4 pupils
= 4 x 98
= 392
Total marks scored after 4 pupils transferred out
= 50 x (1 u - 4)
= 50 u - 200
56 u - 392 = 50 u - 200
56 u - 50 u = 392 - 200
6 u = 192
1 u = 192 ÷ 6 = 32
Number of pupils in the class at first
= 1 u
= 32
Answer(s): 32