In August, the ratio of boys and girls in a school's Band was 3 : 7. In September, 41 new members joined the club. As a result, the ratio of boys to girls in the club became 5 : 4. There were 12 boys in the Band in August. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
3 u |
7 u |
| Change |
+ 41 |
| After |
5 p |
4 p |
Number of boys at first = 3 u
3 u = 12
1 u = 12 ÷ 3 = 4
Total number of members at first
= 3 u + 7 u
= 10 u
= 10 x 4
= 40
Total number of members in the end
= 40 + 41
= 81
Total number of members in the end
= 5 p + 4 p
= 9 p
9 p = 81
1 p = 81 ÷ 9 = 9
Number of girls in the end
= 4 p
= 4 x 9
= 36
Number of girls at first
= 7 u
= 7 x 4
= 28
Number of new members who were girls
= 36 - 28
= 8
Answer(s): 8
