In October, the ratio of girls and boys in a school's Computer Club was 2 : 5. In November, 75 new members joined the club. As a result, the ratio of girls to boys in the club became 6 : 5. There were 10 girls in the Computer Club in October. How many of the new members were boys?
| |
Girls |
Boys |
| Before |
2 u |
5 u |
| Change |
+ 75 |
| After |
6 p |
5 p |
Number of girls at first = 2 u
2 u = 10
1 u = 10 ÷ 2 = 5
Total number of members at first
= 2 u + 5 u
= 7 u
= 7 x 5
= 35
Total number of members in the end
= 35 + 75
= 110
Total number of members in the end
= 6 p + 5 p
= 11 p
11 p = 110
1 p = 110 ÷ 11 = 10
Number of boys in the end
= 5 p
= 5 x 10
= 50
Number of boys at first
= 5 u
= 5 x 5
= 25
Number of new members who were boys
= 50 - 25
= 25
Answer(s): 25
