In November, the ratio of boys and girls in a school's Swimming Club was 3 : 5. In December, 42 new members joined the club. As a result, the ratio of boys to girls in the club became 6 : 5. There were 9 boys in the Swimming Club in November. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
3 u |
5 u |
| Change |
+ 42 |
| After |
6 p |
5 p |
Number of boys at first = 3 u
3 u = 9
1 u = 9 ÷ 3 = 3
Total number of members at first
= 3 u + 5 u
= 8 u
= 8 x 3
= 24
Total number of members in the end
= 24 + 42
= 66
Total number of members in the end
= 6 p + 5 p
= 11 p
11 p = 66
1 p = 66 ÷ 11 = 6
Number of girls in the end
= 5 p
= 5 x 6
= 30
Number of girls at first
= 5 u
= 5 x 3
= 15
Number of new members who were girls
= 30 - 15
= 15
Answer(s): 15
