In September, the ratio of girls and boys in a school's Gardening Club was 3 : 7. In October, 60 new members joined the club. As a result, the ratio of girls to boys in the club became 6 : 5. There were 15 girls in the Gardening Club in September. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
3 u |
7 u |
| Change |
+ 60 |
| After |
6 p |
5 p |
Number of girls at first = 3 u
3 u = 15
1 u = 15 ÷ 3 = 5
Total number of members at first
= 3 u + 7 u
= 10 u
= 10 x 5
= 50
Total number of members in the end
= 50 + 60
= 110
Total number of members in the end
= 6 p + 5 p
= 11 p
11 p = 110
1 p = 110 ÷ 11 = 10
Number of boys in the end
= 5 p
= 5 x 10
= 50
Number of boys at first
= 7 u
= 7 x 5
= 35
Number of new members who were boys
= 50 - 35
= 15
Answer(s): 15
