In February, the ratio of boys and girls in a school's Swimming Club was 3 : 7. In March, 80 new members joined the club. As a result, the ratio of boys to girls in the club became 7 : 6. There were 15 boys in the Swimming Club in February. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
3 u |
7 u |
| Change |
+ 80 |
| After |
7 p |
6 p |
Number of boys at first = 3 u
3 u = 15
1 u = 15 ÷ 3 = 5
Total number of members at first
= 3 u + 7 u
= 10 u
= 10 x 5
= 50
Total number of members in the end
= 50 + 80
= 130
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 130
1 p = 130 ÷ 13 = 10
Number of girls in the end
= 6 p
= 6 x 10
= 60
Number of girls at first
= 7 u
= 7 x 5
= 35
Number of new members who were girls
= 60 - 35
= 25
Answer(s): 25
