The ratio of the girls to the boys in a school was 7 : 3. After 16 girls went home and 18 new boys came, there were 6 more girls than boys in the end. Find the number of pupils in the school in the end.
|
Girls (1) |
Boys (2) |
(3) |
Before |
7 u |
3 u |
3 u |
Change |
- 16 |
+ 18 |
+ 18 + 6 = + 24 |
After |
7 u |
3 u + 18 |
3 u + 24 |
Comparing girls and boys in the end |
6 more |
|
|
Since the number of girls is 6 more than the number of boys in the end, when we
add 6 to (2) to form (3), the number of girls and boys in the end will be the same.
(1) = (3)
7 u - 16 = 3 u + 24
7 u - 3 u = 24 + 16
4 u = 40
1 u = 40 ÷ 4 = 10
Number of pupils in the end
= 7 u + 3 u - 16 + 18
= 10 u + 2
= 10 x 10 + 2
= 100 + 2
= 102
Answer(s): 102