In February, the ratio of girls and boys in a school's Swimming Club was 4 : 7. In March, 46 new members joined the club. As a result, the ratio of girls to boys in the club became 5 : 4. There were 16 girls in the Swimming Club in February. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
4 u |
7 u |
| Change |
+ 46 |
| After |
5 p |
4 p |
Number of girls at first = 4 u
4 u = 16
1 u = 16 ÷ 4 = 4
Total number of members at first
= 4 u + 7 u
= 11 u
= 11 x 4
= 44
Total number of members in the end
= 44 + 46
= 90
Total number of members in the end
= 5 p + 4 p
= 9 p
9 p = 90
1 p = 90 ÷ 9 = 10
Number of boys in the end
= 4 p
= 4 x 10
= 40
Number of boys at first
= 7 u
= 7 x 4
= 28
Number of new members who were boys
= 40 - 28
= 12
Answer(s): 12
