There were 12 more boys than girls in the canteen. Excluding 11 girls, the number of girls was
23 of the number of boys. When another 7 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 |
12 more |
|
Before |
3 u |
2 u + 11 |
Change |
+ 7 |
|
After |
3 u + 7 |
2 u + 11 |
Number of boys at first was 12 more than the number of girls. If another 12 girls entered the canteen at first, the number of boys and girls at first would be the same.
3 u = 2 u + 11 + 12
3 u - 2 u = 11 + 12
1 u = 23
Total number of boys in the end
= 3 u + 7
= 3 x 23 + 7
= 69 + 7
= 76
Total number of pupils in the end
= 3 u + 7 + 2 u + 11
= 5 u + 18
= 5 x 23 + 18
= 133
Fraction of the pupils who were boys in the end
=
76133 =
47 Answer(s):
47