There were 4 more boys than girls in the school hall. Excluding 8 girls, the number of girls was
45 of the number of boys. When another 12 boys joined, what fraction of the pupils were boys in the end? Give your answer in its simplest form.
|
Boys |
Girls |
Comparing boys and girls at first |
4 more |
|
Before |
5 u |
4 u + 8 |
Change |
+ 12 |
|
After |
5 u + 12 |
4 u + 8 |
Number of boys at first was 4 more than the number of girls. If another 4 girls entered the school hall at first, the number of boys and girls at first would be the same.
5 u = 4 u + 8 + 4
5 u - 4 u = 8 + 4
1 u = 12
Total number of boys in the end
= 5 u + 12
= 5 x 12 + 12
= 60 + 12
= 72
Total number of pupils in the end
= 5 u + 12 + 4 u + 8
= 9 u + 20
= 9 x 12 + 20
= 128
Fraction of the pupils who were boys in the end
=
72128 =
916 Answer(s):
916