The ratio of the boys to the girls in a school was 7 : 4. After 12 boys went home and 29 new girls came, there were 7 more boys than girls in the end. Find the number of children in the school in the end.
|
Boys (1) |
Girls (2) |
(3) |
Before |
7 u |
4 u |
4 u |
Change |
- 12 |
+ 29 |
+ 29 + 7 = + 36 |
After |
7 u |
4 u + 29 |
4 u + 36 |
Comparing boys and girls in the end |
7 more |
|
|
Since the number of boys is 7 more than the number of girls in the end, when we
add 7 to (2) to form (3), the number of boys and girls in the end will be the same.
(1) = (3)
7 u - 12 = 4 u + 36
7 u - 4 u = 36 + 12
3 u = 48
1 u = 48 ÷ 3 = 16
Number of children in the end
= 7 u + 4 u - 12 + 29
= 11 u + 17
= 11 x 16 + 17
= 176 + 17
= 193
Answer(s): 193