AMC 8 2011 Problem 14

AMC8 2011 年第 14 题

比与比例★★★☆☆

There are 270 students at Colfax Middle School, where the ratio of boys to girls is 5: 4. There are 180 students at Winthrop Middle School, where the ratio of boys to girls is 4: 5. The two schools hold a dance and all students from both schools attend. What fraction of the students at the dance are girls?

中学有 270 个学生，男生和女生的比例是 5:4。Winthrop 中学有 180 个学生，男生和女生的比例是 4:5。这两个学校举行了一次舞会，并且两个学校的学生都参加了这次舞会。那么舞会上女生所占总学生数的比例是多少？

A. $\dfrac7{18}$
B. $\dfrac7{15}$
C. $\dfrac{22}{45}$
D. $\dfrac12$
E. $\dfrac{23}{45}$

正确答案 · Correct Answer

C

解析 · Solution

解析整理中

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