In June, the ratio of girls and boys in a school's Robotics Club was 3 : 8. In July, 112 new members joined the club. As a result, the ratio of girls to boys in the club became 7 : 6. There were 12 girls in the Robotics Club in June. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
3 u |
8 u |
| Change |
+ 112 |
| After |
7 p |
6 p |
Number of girls at first = 3 u
3 u = 12
1 u = 12 ÷ 3 = 4
Total number of members at first
= 3 u + 8 u
= 11 u
= 11 x 4
= 44
Total number of members in the end
= 44 + 112
= 156
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 156
1 p = 156 ÷ 13 = 12
Number of boys in the end
= 6 p
= 6 x 12
= 72
Number of boys at first
= 8 u
= 8 x 4
= 32
Number of new members who were boys
= 72 - 32
= 40
Answer(s): 40
