The average test score of a class was 56 marks. After three students who scored an average marks of 90 marks transferred out of the class, the average score of the remaining students became 53 marks. How many students were there in the class at first?
| |
(1) |
(2) |
| Number |
1 u |
1 u - 3 |
| Value |
56 |
53 |
| Total value |
56 u |
53 u - 159 |
Number of students at first = 1 u
Total score at first
= 1 u x 56
= 56 u
Total score of the 3 students
= 3 x 90
= 270
Total marks scored after 3 students transferred out
= 53 x (1 u - 3)
= 53 u - 159
56 u - 270 = 53 u - 159
56 u - 53 u = 270 - 159
3 u = 111
1 u = 111 ÷ 3 = 37
Number of students in the class at first
= 1 u
= 37
Answer(s): 37
