In April, the ratio of boys and girls in a school's Robotics Club was 4 : 7. In May, 86 new members joined the club. As a result, the ratio of boys to girls in the club became 7 : 6. There were 16 boys in the Robotics Club in April. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
4 u |
7 u |
| Change |
+ 86 |
| After |
7 p |
6 p |
Number of boys at first = 4 u
4 u = 16
1 u = 16 ÷ 4 = 4
Total number of members at first
= 4 u + 7 u
= 11 u
= 11 x 4
= 44
Total number of members in the end
= 44 + 86
= 130
Total number of members in the end
= 7 p + 6 p
= 13 p
13 p = 130
1 p = 130 ÷ 13 = 10
Number of girls in the end
= 6 p
= 6 x 10
= 60
Number of girls at first
= 7 u
= 7 x 4
= 28
Number of new members who were girls
= 60 - 28
= 32
Answer(s): 32
