In January, the ratio of boys and girls in a school's Chess Club was 2 : 5. In February, 85 new members joined the club. As a result, the ratio of boys to girls in the club became 5 : 4. There were 4 boys in the Chess Club in January. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
2 u |
5 u |
| Change |
+ 85 |
| After |
5 p |
4 p |
Number of boys at first = 2 u
2 u = 4
1 u = 4 ÷ 2 = 2
Total number of members at first
= 2 u + 5 u
= 7 u
= 7 x 2
= 14
Total number of members in the end
= 14 + 85
= 99
Total number of members in the end
= 5 p + 4 p
= 9 p
9 p = 99
1 p = 99 ÷ 9 = 11
Number of girls in the end
= 4 p
= 4 x 11
= 44
Number of girls at first
= 5 u
= 5 x 2
= 10
Number of new members who were girls
= 44 - 10
= 34
Answer(s): 34
