In November, the ratio of girls and boys in a school's Art Club was 3 : 5. In December, 90 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 Art Club in November. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
3 u |
5 u |
| Change |
+ 90 |
| 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 + 90
= 130
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 130
1 p = 130 ÷ 13 = 10
Number of boys in the end
= 6 p
= 6 x 10
= 60
Number of boys at first
= 5 u
= 5 x 5
= 25
Number of new members who were boys
= 60 - 25
= 35
Answer(s): 35
