At a school, there were 30 pupils from Club C and 40% less pupils from Club D. Some pupils joined Club D and the ratio of the number of pupils from Club C to the number of pupils from Club D became 6 : 5. How many pupils joined Club D?
|
Club C |
Club D |
Before |
30 |
18 |
Change |
|
+ ? |
After |
6 u |
5 u |
Number of pupils from Club D at first in percent
= 100% - 40%
= 60%
Number of pupils from Club D at first
= 60% x 30
=
60100 x 30
= 18
Number of pupils in Club C remains unchanged.
6 u = 30
1 u = 30 ÷ 6 = 5
Number of pupils from Club D in the end
= 5 u
= 5 x 5
= 25
Number of pupils joined Club D
= 25 - 18
= 7
Answer(s): 7