The ratio of the girls to the boys in a kindergarten was 5 : 3. After 18 girls went home and 20 new boys came, there were 18 more girls than boys in the end. Find the number of children in the kindergarten at first.
| |
Girls
(1) |
Boys
(2) |
(3) |
| Before |
5 u |
3 u |
3 u |
| Change |
- 18 |
+ 20 |
+ 20 + 18 = + 38 |
| After |
5 u |
3 u + 20 |
3 u + 38 |
Comparing girls and
boys in the end |
18 more |
|
|
Since the number of girls is 18 more than the number of boys in the end, when we
add 18 to (2) to form (3), the number of girls and boys in the end will be the same.
(1) = (3)
5 u - 18 = 3 u + 38
5 u - 3 u = 38 + 18
2 u = 56
1 u = 56 ÷ 2 = 28
Number of children at first
= 5 u + 3 u
= 8 u
= 8 x 28
= 224
Answer(s): 224
