The ratio of the boys to the girls in a kindergarten was 7 : 2. After 11 boys went home and 15 new girls came, there were 19 more boys than girls in the end. Find the number of students in the kindergarten in the end.
| |
Boys
(1) |
Girls
(2) |
(3) |
| Before |
7 u |
2 u |
2 u |
| Change |
- 11 |
+ 15 |
+ 15 + 19 = + 34 |
| After |
7 u |
2 u + 15 |
2 u + 34 |
Comparing boys and
girls in the end |
19 more |
|
|
Since the number of boys is 19 more than the number of girls in the end, when we
add 19 to (2) to form (3), the number of boys and girls in the end will be the same.
(1) = (3)
7 u - 11 = 2 u + 34
7 u - 2 u = 34 + 11
5 u = 45
1 u = 45 ÷ 5 = 9
Number of students in the end
= 7 u + 2 u - 11 + 15
= 9 u + 4
= 9 x 9 + 4
= 81 + 4
= 85
Answer(s): 85
