In January, the ratio of boys and girls in a school's Robotics Club was 5 : 8. In February, 25 new members joined the club. As a result, the ratio of boys to girls in the club became 6 : 5. There were 20 boys in the Robotics Club in January. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
5 u |
8 u |
| Change |
+ 25 |
| After |
6 p |
5 p |
Number of boys at first = 5 u
5 u = 20
1 u = 20 ÷ 5 = 4
Total number of members at first
= 5 u + 8 u
= 13 u
= 13 x 4
= 52
Total number of members in the end
= 52 + 25
= 77
Total number of members in the end
= 6 p + 5 p
= 11 p
11 p = 77
1 p = 77 ÷ 11 = 7
Number of girls in the end
= 5 p
= 5 x 7
= 35
Number of girls at first
= 8 u
= 8 x 4
= 32
Number of new members who were girls
= 35 - 32
= 3
Answer(s): 3
