In February, the ratio of boys and girls in a school's Tennis Club was 2 : 5. In March, 57 new members joined the club. As a result, the ratio of boys to girls in the club became 7 : 6. There were 6 boys in the Tennis Club in February. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
2 u |
5 u |
| Change |
+ 57 |
| After |
7 p |
6 p |
Number of boys 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 + 57
= 78
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 78
1 p = 78 ÷ 13 = 6
Number of girls in the end
= 6 p
= 6 x 6
= 36
Number of girls at first
= 5 u
= 5 x 3
= 15
Number of new members who were girls
= 36 - 15
= 21
Answer(s): 21
