At a school, there were 30 boys from Club D and 30% less boys from Club E. Some boys joined Club E and the ratio of the number of boys from Club D to the number of boys from Club E became 5 : 4. How many boys joined Club E?
| |
Club D |
Club E |
| Before |
30 |
21 |
| Change |
|
+ ? |
| After |
5 u |
4 u |
Number of boys from Club E at first in percent
= 100% - 30%
= 70%
Number of boys from Club E at first
= 70% x 30
=
70100 x 30
= 21
Number of boys in Club D remains unchanged.
5 u = 30
1 u = 30 ÷ 5 = 6
Number of boys from Club E in the end
= 4 u
= 4 x 6
= 24
Number of boys joined Club E
= 24 - 21
= 3
Answer(s): 3
