At a school, there were 30 girls from Club C and 30% less girls from Club D. Some girls joined Club D and the ratio of the number of girls from Club C to the number of girls from Club D became 6 : 5. How many girls joined Club D?
| |
Club C |
Club D |
| Before |
30 |
21 |
| Change |
|
+ ? |
| After |
6 u |
5 u |
Number of girls from Club D at first in percent
= 100% - 30%
= 70%
Number of girls from Club D at first
= 70% x 30
=
70100 x 30
= 21
Number of girls in Club C remains unchanged.
6 u = 30
1 u = 30 ÷ 6 = 5
Number of girls from Club D in the end
= 5 u
= 5 x 5
= 25
Number of girls joined Club D
= 25 - 21
= 4
Answer(s): 4
