The ratio of the boys to the girls in a kindergarten was 7 : 4. After 14 boys went home and 17 new girls came, there were 8 more boys than girls in the end. Find the number of students in the kindergarten at first.
| |
Boys
(1) |
Girls
(2) |
(3) |
| Before |
7 u |
4 u |
4 u |
| Change |
- 14 |
+ 17 |
+ 17 + 8 = + 25 |
| After |
7 u |
4 u + 17 |
4 u + 25 |
Comparing boys and
girls in the end |
8 more |
|
|
Since the number of boys is 8 more than the number of girls in the end, when we
add 8 to (2) to form (3), the number of boys and girls in the end will be the same.
(1) = (3)
7 u - 14 = 4 u + 25
7 u - 4 u = 25 + 14
3 u = 39
1 u = 39 ÷ 3 = 13
Number of students at first
= 7 u + 4 u
= 11 u
= 11 x 13
= 143
Answer(s): 143
