In February, the ratio of boys and girls in a school's Bowing Club was 4 : 7. In March, 30 new members joined the club. As a result, the ratio of boys to girls in the club became 4 : 3. There were 12 boys in the Bowing Club in February. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
4 u |
7 u |
| Change |
+ 30 |
| After |
4 p |
3 p |
Number of boys at first = 4 u
4 u = 12
1 u = 12 ÷ 4 = 3
Total number of members at first
= 4 u + 7 u
= 11 u
= 11 x 3
= 33
Total number of members in the end
= 33 + 30
= 63
Total number of members in the end
= 4 p + 3 p
= 7 p
7 p = 63
1 p = 63 ÷ 7 = 9
Number of girls in the end
= 3 p
= 3 x 9
= 27
Number of girls at first
= 7 u
= 7 x 3
= 21
Number of new members who were girls
= 27 - 21
= 6
Answer(s): 6
