In February, the ratio of girls and boys in a school's Swimming Club was 2 : 5. In March, 70 new members joined the club. As a result, the ratio of girls to boys in the club became 7 : 6. There were 6 girls in the Swimming Club in February. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
2 u |
5 u |
| Change |
+ 70 |
| After |
7 p |
6 p |
Number of girls at first = 2 u
2 u = 6
1 u = 6 ÷ 2 = 3
Total number of members at first
= 2 u + 5 u
= 7 u
= 7 x 3
= 21
Total number of members in the end
= 21 + 70
= 91
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 91
1 p = 91 ÷ 13 = 7
Number of boys in the end
= 6 p
= 6 x 7
= 42
Number of boys at first
= 5 u
= 5 x 3
= 15
Number of new members who were boys
= 42 - 15
= 27
Answer(s): 27
