In June, the ratio of girls and boys in a school's Dance Club was 3 : 7. In July, 126 new members joined the club. As a result, the ratio of girls to boys in the club became 7 : 6. There were 9 girls in the Dance Club in June. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
3 u |
7 u |
| Change |
+ 126 |
| After |
7 p |
6 p |
Number of girls at first = 3 u
3 u = 9
1 u = 9 ÷ 3 = 3
Total number of members at first
= 3 u + 7 u
= 10 u
= 10 x 3
= 30
Total number of members in the end
= 30 + 126
= 156
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 156
1 p = 156 ÷ 13 = 12
Number of boys in the end
= 6 p
= 6 x 12
= 72
Number of boys at first
= 7 u
= 7 x 3
= 21
Number of new members who were boys
= 72 - 21
= 51
Answer(s): 51
