The ratio of the girls to the boys in a kindergarten was 5 : 2. After 26 girls went home and 26 new boys came, there were 20 more girls than boys in the end. Find the number of students in the kindergarten at first.
| |
Girls
(1) |
Boys
(2) |
(3) |
| Before |
5 u |
2 u |
2 u |
| Change |
- 26 |
+ 26 |
+ 26 + 20 = + 46 |
| After |
5 u |
2 u + 26 |
2 u + 46 |
Comparing girls and
boys in the end |
20 more |
|
|
Since the number of girls is 20 more than the number of boys in the end, when we
add 20 to (2) to form (3), the number of girls and boys in the end will be the same.
(1) = (3)
5 u - 26 = 2 u + 46
5 u - 2 u = 46 + 26
3 u = 72
1 u = 72 ÷ 3 = 24
Number of students at first
= 5 u + 2 u
= 7 u
= 7 x 24
= 168
Answer(s): 168
