In March, the ratio of boys and girls in a school's Robotics Club was 3 : 5. In April, 37 new members joined the club. As a result, the ratio of boys to girls in the club became 4 : 3. There were 15 boys in the Robotics Club in March. How many of the new members were girls?
|
Boys |
Girls |
Before |
3 u |
5 u |
Change |
+ 37 |
After |
4 p |
3 p |
Number of boys 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 + 37
= 77
Total number of members in the end
= 4 p + 3 p
= 7 p
7 p = 77
1 p = 77 ÷ 7 = 11
Number of girls in the end
= 3 p
= 3 x 11
= 33
Number of girls at first
= 5 u
= 5 x 5
= 25
Number of new members who were girls
= 33 - 25
= 8
Answer(s): 8