In August, the ratio of boys and girls in a school's Robotics Club was 3 : 7. In September, 26 new members joined the club. As a result, the ratio of boys to girls in the club became 6 : 5. There were 12 boys in the Robotics Club in August. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
3 u |
7 u |
| Change |
+ 26 |
| After |
6 p |
5 p |
Number of boys at first = 3 u
3 u = 12
1 u = 12 ÷ 3 = 4
Total number of members at first
= 3 u + 7 u
= 10 u
= 10 x 4
= 40
Total number of members in the end
= 40 + 26
= 66
Total number of members in the end
= 6 p + 5 p
= 11 p
11 p = 66
1 p = 66 ÷ 11 = 6
Number of girls in the end
= 5 p
= 5 x 6
= 30
Number of girls at first
= 7 u
= 7 x 4
= 28
Number of new members who were girls
= 30 - 28
= 2
Answer(s): 2
