At a school, there were 50 boys from Club Y and 40% less boys from Club Z. Some boys joined Club Z and the ratio of the number of boys from Club Y to the number of boys from Club Z became 5 : 4. How many boys joined Club Z?
| |
Club Y |
Club Z |
| Before |
50 |
30 |
| Change |
|
+ ? |
| After |
5 u |
4 u |
Number of boys from Club Z at first in percent
= 100% - 40%
= 60%
Number of boys from Club Z at first
= 60% x 50
=
60100 x 50
= 30
Number of boys in Club Y remains unchanged.
5 u = 50
1 u = 50 ÷ 5 = 10
Number of boys from Club Z in the end
= 4 u
= 4 x 10
= 40
Number of boys joined Club Z
= 40 - 30
= 10
Answer(s): 10
