In November, the ratio of boys and girls in a school's Tennis Club was 4 : 7. In December, 49 new members joined the club. As a result, the ratio of boys to girls in the club became 7 : 6. There were 20 boys in the Tennis Club in November. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
4 u |
7 u |
| Change |
+ 49 |
| After |
7 p |
6 p |
Number of boys at first = 4 u
4 u = 20
1 u = 20 ÷ 4 = 5
Total number of members at first
= 4 u + 7 u
= 11 u
= 11 x 5
= 55
Total number of members in the end
= 55 + 49
= 104
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 104
1 p = 104 ÷ 13 = 8
Number of girls in the end
= 6 p
= 6 x 8
= 48
Number of girls at first
= 7 u
= 7 x 5
= 35
Number of new members who were girls
= 48 - 35
= 13
Answer(s): 13
