In November, the ratio of boys and girls in a school's Computer Club was 5 : 8. In December, 43 new members joined the club. As a result, the ratio of boys to girls in the club became 5 : 4. There were 25 boys in the Computer Club in November. How many of the new members were girls?
| |
Boys |
Girls |
| Before |
5 u |
8 u |
| Change |
+ 43 |
| After |
5 p |
4 p |
Number of boys at first = 5 u
5 u = 25
1 u = 25 ÷ 5 = 5
Total number of members at first
= 5 u + 8 u
= 13 u
= 13 x 5
= 65
Total number of members in the end
= 65 + 43
= 108
Total number of members in the end
= 5 p + 4 p
= 9 p
9 p = 108
1 p = 108 ÷ 9 = 12
Number of girls in the end
= 4 p
= 4 x 12
= 48
Number of girls at first
= 8 u
= 8 x 5
= 40
Number of new members who were girls
= 48 - 40
= 8
Answer(s): 8
