The ratio of the boys to the girls in a school was 8 : 5. After 20 boys went home and 22 new girls came, there were 6 more boys than girls in the end. Find the number of pupils in the school in the end.
| |
Boys
(1) |
Girls
(2) |
(3) |
| Before |
8 u |
5 u |
5 u |
| Change |
- 20 |
+ 22 |
+ 22 + 6 = + 28 |
| After |
8 u |
5 u + 22 |
5 u + 28 |
Comparing boys and
girls in the end |
6 more |
|
|
Since the number of boys is 6 more than the number of girls in the end, when we
add 6 to (2) to form (3), the number of boys and girls in the end will be the same.
(1) = (3)
8 u - 20 = 5 u + 28
8 u - 5 u = 28 + 20
3 u = 48
1 u = 48 ÷ 3 = 16
Number of pupils in the end
= 8 u + 5 u - 20 + 22
= 13 u + 2
= 13 x 16 + 2
= 208 + 2
= 210
Answer(s): 210
