The ratio of the girls to the boys in a school was 7 : 3. After 15 girls went home and 21 new boys came, there were 8 more girls than boys in the end. Find the number of children in the school in the end.
|
Girls (1) |
Boys (2) |
(3) |
Before |
7 u |
3 u |
3 u |
Change |
- 15 |
+ 21 |
+ 21 + 8 = + 29 |
After |
7 u |
3 u + 21 |
3 u + 29 |
Comparing girls and boys in the end |
8 more |
|
|
Since the number of girls is 8 more than the number of boys in the end, when we
add 8 to (2) to form (3), the number of girls and boys in the end will be the same.
(1) = (3)
7 u - 15 = 3 u + 29
7 u - 3 u = 29 + 15
4 u = 44
1 u = 44 ÷ 4 = 11
Number of children in the end
= 7 u + 3 u - 15 + 21
= 10 u + 6
= 10 x 11 + 6
= 110 + 6
= 116
Answer(s): 116