In November, the ratio of boys and girls in a school's Tennis Club was 3 : 5. In December, 32 new members joined the club. As a result, the ratio of boys to girls in the club became 5 : 4. There were 15 boys in the Tennis Club in November. How many of the new members were girls?
|
Boys |
Girls |
Before |
3 u |
5 u |
Change |
+ 32 |
After |
5 p |
4 p |
Number of boys at first = 3 u
3 u = 15
1 u = 15 ÷ 3 = 5
Total number of members at first
= 3 u + 5 u
= 8 u
= 8 x 5
= 40
Total number of members in the end
= 40 + 32
= 72
Total number of members in the end
= 5 p + 4 p
= 9 p
9 p = 72
1 p = 72 ÷ 9 = 8
Number of girls in the end
= 4 p
= 4 x 8
= 32
Number of girls at first
= 5 u
= 5 x 5
= 25
Number of new members who were girls
= 32 - 25
= 7
Answer(s): 7