In February, the ratio of girls and boys in a school's Band was 3 : 5. In March, 38 new members joined the club. As a result, the ratio of girls to boys in the club became 7 : 6. There were 15 girls in the Band in February. How many of the new members were boys?
|
Girls |
Boys |
Before |
3 u |
5 u |
Change |
+ 38 |
After |
7 p |
6 p |
Number of girls 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 + 38
= 78
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 78
1 p = 78 ÷ 13 = 6
Number of boys in the end
= 6 p
= 6 x 6
= 36
Number of boys at first
= 5 u
= 5 x 5
= 25
Number of new members who were boys
= 36 - 25
= 11
Answer(s): 11