In November, the ratio of boys and girls in a school's Swimming Club was 2 : 5. In December, 128 new members joined the club. As a result, the ratio of boys to girls in the club became 7 : 6. There were 8 boys in the Swimming Club in November. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
2 u |
5 u |
| Change |
+ 128 |
| After |
7 p |
6 p |
Number of boys at first = 2 u
2 u = 8
1 u = 8 ÷ 2 = 4
Total number of members at first
= 2 u + 5 u
= 7 u
= 7 x 4
= 28
Total number of members in the end
= 28 + 128
= 156
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 156
1 p = 156 ÷ 13 = 12
Number of girls in the end
= 6 p
= 6 x 12
= 72
Number of girls at first
= 5 u
= 5 x 4
= 20
Number of new members who were girls
= 72 - 20
= 52
Answer(s): 52
