The ratio of the girls to the boys in a kindergarten was 7 : 4. After 10 girls went home and 20 new boys came, there were 6 more girls than boys in the end. Find the number of students in the kindergarten at first.
|
Girls (1) |
Boys (2) |
(3) |
Before |
7 u |
4 u |
4 u |
Change |
- 10 |
+ 20 |
+ 20 + 6 = + 26 |
After |
7 u |
4 u + 20 |
4 u + 26 |
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 - 10 = 4 u + 26
7 u - 4 u = 26 + 10
3 u = 36
1 u = 36 ÷ 3 = 12
Number of students at first
= 7 u + 4 u
= 11 u
= 11 x 12
= 132
Answer(s): 132