In June, the ratio of girls and boys in a school's Badminton Club was 5 : 8. In July, 39 new members joined the club. As a result, the ratio of girls to boys in the club became 7 : 6. There were 15 girls in the Badminton Club in June. How many of the new members were boys?
|
Girls |
Boys |
Before |
5 u |
8 u |
Change |
+ 39 |
After |
7 p |
6 p |
Number of girls at first = 5 u
5 u = 15
1 u = 15 ÷ 5 = 3
Total number of members at first
= 5 u + 8 u
= 13 u
= 13 x 3
= 39
Total number of members in the end
= 39 + 39
= 78
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 78
1 p = 78 ÷ 13 = 6
Number of boys in the end
= 6 p
= 6 x 6
= 36
Number of boys at first
= 8 u
= 8 x 3
= 24
Number of new members who were boys
= 36 - 24
= 12
Answer(s): 12