In February, the ratio of girls and boys in a school's Swimming Club was 2 : 5. In March, 35 new members joined the club. As a result, the ratio of girls to boys in the club became 4 : 3. There were 4 girls in the Swimming Club in February. How many of the new members were boys?
|
Girls |
Boys |
Before |
2 u |
5 u |
Change |
+ 35 |
After |
4 p |
3 p |
Number of girls at first = 2 u
2 u = 4
1 u = 4 ÷ 2 = 2
Total number of members at first
= 2 u + 5 u
= 7 u
= 7 x 2
= 14
Total number of members in the end
= 14 + 35
= 49
Total number of members in the end
= 4 p + 3 p
= 7 p
7 p = 49
1 p = 49 ÷ 7 = 7
Number of boys in the end
= 3 p
= 3 x 7
= 21
Number of boys at first
= 5 u
= 5 x 2
= 10
Number of new members who were boys
= 21 - 10
= 11
Answer(s): 11