In April, the ratio of boys and girls in a school's Robotics Club was 3 : 8. In May, 110 new members joined the club. As a result, the ratio of boys to girls in the club became 7 : 6. There were 9 boys in the Robotics Club in April. How many of the new members were girls?
|
Boys |
Girls |
Before |
3 u |
8 u |
Change |
+ 110 |
After |
7 p |
6 p |
Number of boys at first = 3 u
3 u = 9
1 u = 9 ÷ 3 = 3
Total number of members at first
= 3 u + 8 u
= 11 u
= 11 x 3
= 33
Total number of members in the end
= 33 + 110
= 143
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 143
1 p = 143 ÷ 13 = 11
Number of girls in the end
= 6 p
= 6 x 11
= 66
Number of girls at first
= 8 u
= 8 x 3
= 24
Number of new members who were girls
= 66 - 24
= 42
Answer(s): 42