In September, the ratio of girls and boys in a school's Badminton Club was 3 : 7. In October, 48 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 Badminton Club in September. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
3 u |
7 u |
| Change |
+ 48 |
| 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 + 48
= 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
= 7 u
= 7 x 3
= 21
Number of new members who were boys
= 36 - 21
= 15
Answer(s): 15
