In July, the ratio of girls and boys in a school's Dance Club was 3 : 7. In August, 97 new members joined the club. As a result, the ratio of girls to boys in the club became 7 : 6. There were 6 girls in the Dance Club in July. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
3 u |
7 u |
| Change |
+ 97 |
| After |
7 p |
6 p |
Number of girls at first = 3 u
3 u = 6
1 u = 6 ÷ 3 = 2
Total number of members at first
= 3 u + 7 u
= 10 u
= 10 x 2
= 20
Total number of members in the end
= 20 + 97
= 117
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 117
1 p = 117 ÷ 13 = 9
Number of boys in the end
= 6 p
= 6 x 9
= 54
Number of boys at first
= 7 u
= 7 x 2
= 14
Number of new members who were boys
= 54 - 14
= 40
Answer(s): 40
