In April, the ratio of boys and girls in a school's Chess Club was 3 : 5. In May, 60 new members joined the club. As a result, the ratio of boys to girls in the club became 4 : 3. There were 9 boys in the Chess Club in April. How many of the new members were girls?
|
Boys |
Girls |
Before |
3 u |
5 u |
Change |
+ 60 |
After |
4 p |
3 p |
Number of boys at first = 3 u
3 u = 9
1 u = 9 ÷ 3 = 3
Total number of members at first
= 3 u + 5 u
= 8 u
= 8 x 3
= 24
Total number of members in the end
= 24 + 60
= 84
Total number of members in the end
= 4 p + 3 p
= 7 p
7 p = 84
1 p = 84 ÷ 7 = 12
Number of girls in the end
= 3 p
= 3 x 12
= 36
Number of girls at first
= 5 u
= 5 x 3
= 15
Number of new members who were girls
= 36 - 15
= 21
Answer(s): 21